Method of describing object region data, apparatus for generating object region data, video processing apparatus and video processing method

ABSTRACT

A region data describing method for describing, over a plurality of frames, region data about the region of an arbitrary object in a video, the method specifying the object region in the video with at least either of an approximate figure approximating the region or characteristic points of the region, approximating a trajectory obtained by arranging position data of the representative points or the characteristic point in a direction in which frames proceed with a predetermined function and describing the parameter of the function as region data. Thus, the region of a predetermined object in the video can be described with a small quantity of data. Moreover, creation and handling of data can easily be performed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 11-187033, filed Jun. 30,1999, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a method of describing object regiondata such that information about an object region in a video isdescribed, an apparatus for generating object region data such thatinformation about an object region in a video is generated, a videoprocessing apparatus arranged to be given an instruction about an objectin a video to perform a predetermined process or retrieve an object in avideo, and a video processing method therefor.

Hyper media are configured such that related information called a hyperlink is given in between mediums, such as videos, sounds or texts, topermit mutual reference. When videos are mainly used, relatedinformation has been provided for each object which appears in thevideo. When the object is specified, related information (textinformation or the like) is displayed. The foregoing structure is arepresentative example of the hyper media. The object in the video isexpressed by a frame number or a time stamp of the video, andinformation for identifying a region in the video which are recorded invideo data or recorded as individual data.

Mask images have frequently been used as means for identifying a regionin a video. The mask image is a bit map image constituted by givingdifferent pixel values between the inside portion of an identifiedregion and the outside portion of the same. A simplest method has anarrangement that a pixel value of “1” is given to the inside portion ofthe region and “0” is given to the outside portion of the same.Alternatively, α values which are employed in computer graphics aresometimes employed. Since the α value is usually able to express 256levels of gray, a portion of the levels is used. The inside portion ofthe specified region is expressed as 255, while the outside portion ofthe same is expressed as 0. The latter image is called an α map. Whenthe regions in the image are expressed by the mask images, determinationwhether or not a pixel in a frame is included in the specified regioncan easily be made by reading the value of the pixel of the mask imageand by determining whether the value is 0 or 255. The mask image hasfreedom with which a region can be expressed regardless of the shape ofthe region and even a discontinuous region can be expressed. The maskimage must have pixels, the size of which is the same as the size of theoriginal image. Thus, there arises a problem in that the quantity ofdata cannot be reduced.

To reduce the quantity of data of the mask image, the mask image isfrequently compressed. When the mask image is a binary mask imageconstituted by 0 and 1, a process of a binary image can be performed.Therefore, the compression method employed in facsimile machines or thelike is frequently employed. In the case of MPEG-4 in which ISO/IEC MPEG(Moving Picture Experts Group) has been standardized, an arbitrary shapecoding method will be employed in which the mask image constituted by 0and 1 and the mask image using the α value are compressed. The foregoingcompression method is a method using motion compensation and capable ofimproving compression efficiency. On the other hand, complex compressionand decoding processes are required.

To express a region in a video, the mask image or the compressed maskimage has usually been employed. However, data for identifying a regionis required to permit easy and quick extraction, to be reduced inquantity and to permit easy handling.

On the other hand, the hyper media, which are usually assumed that anoperation for displaying related information of a moving object in avideo is performed, have somewhat difficulty in specifying the object asdistinct from handling of a still image. A user usually has difficultyin specifying a specific portion. Therefore, it can be considered thatthe user usually aims, for example, a portion in the vicinity of thecenter of the object in a rough manner. Moreover, a portion adjacent tothe object which is deviated from the object is frequently specifiedaccording to the movement of the object. Therefore, data for specifyinga region is desired to be adaptable to the foregoing media. Moreover, anaiding mechanism for facilitating specification of a moving object in avideo is required for the system for displaying related information ofthe moving object in the video.

As described above, the conventional method of expressing a desiredobject region in a video by using the mask image suffers from a problemin that the quantity of data cannot be reduced. The method arranged tocompress the mask image raises a problem in that coding and decodingbecome too complicated. What is worse, directly accessing to the pixelof a predetermined frame cannot be performed, causing handling to becomedifficult.

There arises another problem in that a device for permitting a user toeasily instruct a moving object in a video has not been provided.

BRIEF SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide amethod of describing object region data and an apparatus for generatingobject region data which are capable of describing a desired objectregion in a video by using a small quantity of data and facilitatinggeneration of data and handling of the same.

Another object of the present invention is to provide a method ofdescribing object region data, an apparatus for generating object regiondata, a video processing method and a video processing apparatus withwhich a user is permitted to easily instruct an object in a video anddetermine the object.

Another object of the present invention is to provide a method ofdescribing object region data, an apparatus for generating object regiondata, a video processing method and a video processing apparatus withwhich retrieval of an object in a video can easily be performed.

According to one aspect of the present invention, there is provided amethod of describing object region data such that information about anarbitrary object region in a video is described over a plurality ofcontinuous frames, the method identifying a desired object region in avideo according to at least either of a figure approximated to theobject region or a characteristic point of the object region;approximating a trajectory obtained by arranging positions ofrepresentative points of the approximate figure or the characteristicpoints of the object region in a direction in which frames proceed witha predetermined function; and describing information about the objectregion by using the parameter of the function.

According to another aspect of the present invention, there is provideda method of describing object region data such that information about anarbitrary object region in a video is described over a plurality ofcontinuous frames, the method describing the object region data by usinginformation capable of identifying at least the frame number of aleading frame and the frame number of a trailing frame of the pluralityof the subject frames or the time stamp of the leading frame and thetime stamp of the trailing frame, information for identifying the typeof the figure of an approximate figure approximating the object region,and the parameter of a function with which a trajectory obtained byarranging position data of representative points of the approximatefigure corresponding to the object region in a direction in which framesproceed has been approximated.

According to another aspect of the present invention, there is provideda method of describing object region data such that information about anarbitrary object region in a video is described over a plurality ofcontinuous frames, the method describing the object region data by usinginformation capable of identifying at least the frame number of aleading frame and the frame number of a trailing frame of the pluralityof the subject frames or the time stamp of the leading frame and thetime stamp of the trailing frame, the number of approximate figuresapproximating the object region, information for identifying the type ofthe figure of an approximate figure and the parameters of functions withwhich trajectories corresponding to the approximate figures and obtainedby arranging position data of representative points of each approximatefigure in a direction in which frames proceed have been approximated.

According to another aspect of the present invention, there is provideda method of describing object region data such that information about anarbitrary object region in a video is described over a plurality ofcontinuous frames, the method describing the object region data by usinginformation capable of identifying at least the frame number of aleading frame and the frame number of a trailing frame of the pluralityof the subject frames or the time stamp of the leading frame and thetime stamp of the trailing frame, and the parameter of a function withwhich a trajectory obtained by arranging position data of characteristicpoints of the object region in a direction in which frames proceed hasbeen approximated.

Information capable of identifying the frame number of a leading frameand the frame number of a trailing frame of the plurality of the subjectframes or the time stamp of the leading frame and the time stamp of thetrailing frame is the leading frame number and a trailing frame numberor the leading frame number and the difference between the leading framenumber and the trailing frame number.

The parameter of the function may be position data of knots of thetrajectory and information arranged to be used together with theposition data of the knots to be capable of identifying the trajectory.Alternatively, the parameter of the function may be a coefficient of thefunction.

When a plurality of representative points of the approximate figure ofthe object region or characteristic points of the object region exist,it is desirable to identify the correspondence between the pluralrepresentative points or the characteristic points of the present frameand a plurality of representative points or characteristic points of anadjacent frame.

It is desirable to describe information related to the object or amethod of accessing to the related information.

According to another aspect of the present invention, there is provideda recording medium storing object region data containing informationabout regions of one or more objects described by one of the abovemethods.

According to another aspect of the present invention, there is provideda recording medium storing object region data containing informationabout regions of one or more objects described by one of the abovemethods and information related to each object or information indicatinga method of accessing to the related information.

According to another aspect of the present invention, there is provideda recording medium storing object region data containing informationabout regions of one or more objects described by one of the abovemethods and information for identifying information related to eachobject, and information related to each object.

According to another aspect of the present invention, there is provideda video processing method for determining whether or not a predeterminedobject has been specified in a screen which is displaying a video, themethod obtaining information describing parameter of a functionapproximating a trajectory obtained by arranging position data ofrepresentative points of the approximate figure in a direction in whichframes proceed when an arbitrary position has been specified in thescreen in a case where a region of the predetermined object exists inthe video; detecting the position of the representative point in theframe based on the obtained information; detecting the position of theapproximate figure in accordance with the detected position of therepresentative point; determining whether or not the input positionexists in the approximate figure; and determining that the predeterminedobject has been specified when a determination has been made that theinput position exists in the approximate figure.

According to another aspect of the present invention, there is provideda video processing method for determining whether or not a predeterminedobject has been specified in a screen which is displaying a video, themethod obtaining information describing parameter of a functionapproximating a trajectory obtained by arranging position data ofcharacteristic points of the object region in a direction in whichframes proceed when an arbitrary position has been specified in thescreen in a case where a region of the predetermined object exists inthe video; detecting the positions of the characteristic points in theframe in accordance with the obtained information; determining whetheror not the distance between the input position and the detected positionof the characteristic point is shorter than a reference value; anddetermining that the predetermined object has been specified when adetermination has been made that the distance is shorter than thereference value.

When a determination has been made that the predetermined object hasbeen specified, it is desirable to show information related to thepredetermined object.

According to another aspect of the present invention, there is provideda video processing method of displaying a region in which apredetermined object exists when the predetermined object has beenspecified in a screen which is displaying a video, the video processingmethod obtaining information describing parameter of a functionapproximating a trajectory obtained by arranging position data of atleast representative points of an approximate figure of the objectregion or characteristic points of the object region in a direction inwhich frames proceed when the region of the predetermined object existsin the video; detecting the representative point or the characteristicpoint in the frame in accordance with the obtained information; anddisplaying information for displaying the position of the object regionin the screen in a predetermined form of display in accordance with thedetected representative point or the characteristic point.

According to another aspect of the present invention, there is provideda video processing method for retrieving a predetermined object amongobjects which appears in a video and which satisfies a predeterminedcondition, the video processing method inputting an arbitrary positionin the video and a retrieving condition determined in accordance withthe input position; obtaining information describing parameter of afunction approximating a trajectory obtained by arranging position dataof representative points of an approximate figure of an object regionproduced for each object which appears in the video or a characteristicpoint of the object region in a direction in which frames proceed;determining, for each object over a plurality of frames, whether or notthe representative point of the approximate figure or the characteristicpoint and the input position have a predetermined relationship in oneframe of one object obtained in accordance with the obtainedinformation; and detecting the predetermined object satisfying theretrieving condition in accordance with a result of determination.

The predetermined relationship may be the relationship that the inputposition exists in the approximate figure region or the relationshipthat the distance from the characteristic point to the input position isshorter than a reference value. The retrieving condition may be acondition of an object which is to be extracted, which is selected froma retrieval condition group consisting of a condition that at least oneframe satisfying the predetermined relationship exists at the inputposition, a condition that the predetermined number of frames eachsatisfying the predetermined relationship exists successively withregard to the input position and a condition that the predeterminedrelationship is not satisfied in all of the frames.

The retrieval condition group includes, as a condition which must beadded to the condition which is determined in accordance with theposition, an attribute condition which must be satisfied by theapproximate figure of the object.

According to another aspect of the present invention, there is provideda video processing method for retrieving a predetermined object amongobjects which appears in a video and which satisfies a predeterminedcondition, the video processing method inputting information forspecifying a trajectory of the position in a video which is to beretrieved; obtaining information describing parameter of a functionapproximating a trajectory obtained by arranging position data ofrepresentative points of an approximate figure of the object regionproduced for each object which appears in a video and which is to beretrieved or a characteristic point of the object region in a directionin which frames proceed; evaluating, for each object, similarity of thetrajectory of the representative point or the characteristic point ofthe one object detected in accordance with the obtained information andthe trajectory of the input position; and detecting the predeterminedobject corresponding to the specified trajectory.

Information for specifying the trajectory of the position may be timesequence information including the relationship between the position andtime. The similarity may be evaluated while the positional relationshipis being added.

The specified trajectory may be a trajectory of an object in a videowhich has been specified. Alternatively, a user may be permitted toinput the trajectory by drawing the trajectory on a GUI.

According to another aspect of the present invention, there is providedan object-region-data generating apparatus for generating data aboutdescribed information of a region of an arbitrary object in a video overa plurality of continuous frames, the object-region-data generatingapparatus comprising a circuit configured to approximate an objectregion in the video in a plurality of the subject frames by using apredetermined figure; a detector configured to detect, in the pluralframes, coordinate values of the predetermined number of representativepoints identifying the predetermined figure which has been used in theapproximation; and a circuit configured to approximate a trajectory of atime sequence of the coordinate values of the representative pointsobtained over the plurality of the continuous frames with apredetermined function, so that information about the object region isgenerated by using the parameter of the function.

According to another aspect of the present invention, there is providedan object-region-data generating apparatus for generating data aboutdescribed information of a region of an arbitrary object in a video overa plurality of continuous frames, the object-region-data generatingapparatus comprising a detector configured to detect the coordinatevalues of the predetermined number of characteristic points of an objectregion in a video over the plurality of the subject frames, and acircuit configured to approximate a time sequential trajectory of thecoordinate values of the characteristic points obtained over theplurality of the continuous frames with a predetermined function,wherein the parameter of the function is used to generate informationabout the object region.

According to another aspect of the present invention, there is provideda video processing apparatus for performing a predetermined process whena predetermined object has been specified in a screen which isdisplaying a video, the video processing apparatus comprising a circuitconfigured to obtain a parameter of a function approximating atrajectory obtained by arranging position data of representative pointsof an approximate figure of the object region in a direction in whichframes proceed in a case where a region of a predetermined object existsin the video when an arbitrary position has been specified in the screento detect the position of the representative point in the frame; adetector configured to detect the position of the approximate figure inaccordance with the detected position of the representative point; and acircuit configured to determine whether or not the input position existsin the approximate figure.

According to another aspect of the present invention, there is provideda video processing apparatus for performing a predetermined process whena predetermined object has been specified in a screen which isdisplaying a video, the video processing apparatus comprising a circuitconfigured to obtain a parameter of a function approximating atrajectory obtained by arranging position data of a characteristic pointof the object region in a direction in which frames proceed in a casewhere the region of the predetermined object exists in the video whenarbitrary position has been specified in the screen to detect theposition of the characteristic point in the frame; and a circuitconfigured to determine whether or not the distance between the inputposition and the detected position of the characteristic point isshorter than a reference value.

According to another aspect of the present invention, there is provideda video processing apparatus for performing a predetermined process whena predetermined object has been is specified in a screen which isdisplaying a video, the video processing apparatus comprising a circuitconfigured to obtain a parameter of a function approximating atrajectory obtained by arranging position data of at least arepresentative point of an approximate figure of the object region or acharacteristic point of the object region in a direction in which framesproceed when the region of the predetermined object exists in the videoto detect the representative point or the characteristic point in theframe; and a circuit configured to display information for indicatingthe position of the object region in the screen in a predetermineddisplay form.

According to another aspect of the present invention, there is provideda video processing apparatus for retrieving a predetermined object amongobjects which appears in a video and which satisfies an specifiedcondition, the video processing apparatus comprising a circuitconfigured to obtain information describing parameter of a functionapproximating a trajectory obtained by arranging position data ofrepresentative points of an approximate figure of the object regionproduced for each object which appears in a video which is to beretrieved or a characteristic point of the object region in a directionin which frames proceed when an arbitrary position in the video which isto be retrieved and a retrieving condition determined in accordance withthe position have been input; a circuit configured to determine, foreach object over a plurality of the frames, whether or not theapproximate figure or the characteristic point of one object in oneframe obtained in accordance with the obtained information and the inputposition satisfy a predetermined relationship; and a detector configuredto detect an object which satisfies the retrieving condition inaccordance with a result of the determination.

According to another aspect of the present invention, there is provideda video processing apparatus for retrieving a predetermined object amongobjects which appears in a video and which satisfies an specifiedcondition, the video processing apparatus comprising a circuitconfigured to obtain information describing parameter of a functionapproximating a trajectory obtained by arranging position data ofrepresentative points of an approximate figure of the object regionproduced for each object which appears in the video which is to beretrieved or a characteristic point of the object region in a directionin which frames proceed when information for specifying a trajectory ofthe position in a video which is to be retrieved has been input; acircuit configured to evaluate, for each object, similarity between thetrajectory of the representative point or the characteristic point ofone object obtained in accordance with the obtained information and thetrajectory of the input position; and a detector configured to detectthe predetermined object corresponding to the specified trajectory inaccordance with the evaluated similarity.

Note that the present invention relating to the apparatus may beemployed as the method and the present invention relating to the methodmay be employed as the apparatus.

The present invention relating to the apparatus and the method may beemployed as a recording medium which stores a program for causing acomputer to perform the procedure according to the present invention (orcausing the computer to serve as means corresponding to the presentinvention or causing the computer to realize the function correspondingto the present invention) and which can be read by the computer.

The present invention is configured such that the object region in avideo over a plurality of frames is described as a parameter of afunction approximating a trajectory obtained by arranging position dataof representative points of an approximate figure of the object regionor a characteristic point of the object region in a direction in whichframes proceed. Therefore, the object region in the video over theplural frames can be described with a small quantity of the functionparameters. Hence it follows that the quantity of data required toidentify the object region can effectively be reduced. Moreover,handling can be facilitated. Moreover, extraction of a representativepoint or a characteristic point from the approximate figure orgeneration of the parameter of the approximate curve can easily beperformed. Moreover, generation of an approximate figure from theparameter of the approximate curve can easily be performed.

When the representative point of the approximate figure is employed, afundamental figure, for example, one or more ellipses, are employed suchthat each ellipse is represented by two focal points and another point.Thus, whether or not arbitrary coordinates specified by a user exist inthe object region (the approximate figure) can be determined by using asimple discriminant. Hence it follows that the user is able to easilyinstruct a moving object in a video.

When the characteristic point is employed, whether or not the arbitrarycoordinates specified by a user indicates the object region canconsiderably easily be determined. Thus, a moving object in a video caneasily be specified by the user.

When display of an object region among regions of objects which can beidentified by using object region data and which has relatedinformation, or display of an image indicating the object region iscontrolled, the user is permitted to quickly recognize whether or notrelated information exists and the position of the object region.Therefore, the operation which is performed by the user can effectivelybe aided.

According to the present invention, retrieval of an object in a videocan easily be performed in accordance with a position in a video throughwhich the object passes, residence time at a certain point or atrajectory.

Additional objects and advantages of the present invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the present invention.

The objects and advantages of the present invention may be realized andobtained by means of the instrumentalities and combinations particularlypointed out hereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe present invention and, together with the general description givenabove and the detailed description of the preferred embodiments givenbelow, serve to explain the principles of the present invention inwhich:

FIG. 1 is a diagram showing an example of the structure of anobject-region-data generating apparatus according to a first embodimentof the present invention;

FIGS. 2A, 2B, 2C and 2D are diagrams showing a procedure for describingan object region in a video with object region data;

FIG. 3 is a diagram showing an example of a process for approximating anobject region with an ellipse;

FIG. 4 is a diagram showing an example of a process for detecting arepresentative point of an approximate ellipse of an object region;

FIG. 5 is a diagram showing an example of the structure of object regiondata;

FIG. 6 is a diagram showing an example of the structure of data of anapproximate figure in object region data;

FIG. 7 is a diagram showing an example of the structure of data of atrajectory of a representative point in data of an approximate figure;

FIG. 8 is a diagram showing an example of representative points when theapproximate figure is a parallelogram;

FIG. 9 is a diagram showing an example of representative points when theapproximate figure is a polygon;

FIG. 10 is a flowchart showing an example of a procedure according tothe first embodiment of the present invention;

FIG. 11 is a diagram showing an example in which the object region in avideo is expressed with a plurality of ellipses;

FIG. 12 is a diagram showing an example of the structure of objectregion data including data of a plurality of approximate figures;

FIGS. 13A, 13B and 13C are diagrams schematically showing anotherprocess for describing an object region in a video with object regiondata;

FIG. 14 is a flowchart showing an example of a procedure for obtainingan approximate rectangle;

FIG. 15 is a diagram showing a state in which an inclined and elongatedobject is approximated with a non-inclined rectangle;

FIGS. 16A and 16B are diagrams showing a state in which an object hasbeen approximated with a rectangle having an inclination correspondingto the inclination of the object;

FIG. 17 is a flowchart showing another example of a procedure forobtaining the approximate rectangle;

FIG. 18 is a diagram showing a method of obtaining an approximateellipse from an approximate rectangle;

FIG. 19 is a flowchart showing an example of a procedure for obtainingan approximate ellipse from an approximate rectangle;

FIG. 20 is a diagram showing a method of making representative points ofapproximate figures to correspond to one another between adjacentframes;

FIG. 21 is a flowchart showing an example of a procedure for makingrepresentative points of approximate figures to correspond to oneanother between adjacent frames;

FIG. 22 is a diagram showing another example of the structure of objectregion data;

FIG. 23 is a diagram showing an example of the correspondence among theID of types of figures, the type of the figures and the number ofrepresentative points;

FIG. 24 is a diagram showing an example of the correspondence among theID of a function, the form of the function and the function parameterand the limit condition;

FIG. 25 is a diagram showing a specific example of the structure of dataabout related information;

FIG. 26 is a diagram showing another specific example of the structureof data about related information;

FIG. 27 is a diagram showing an example of an object-region-datagenerating apparatus according to a second embodiment of the presentinvention;

FIG. 28 is a flowchart showing an example of a procedure according tothe second embodiment;

FIG. 29 is a diagram showing an example of the structure of a videoprocessing apparatus according to a third embodiment of the presentinvention;

FIG. 30 is a flowchart showing an example of a procedure according tothe third embodiment;

FIG. 31 is a diagram showing an example of display of contents hypermedia which uses object region data;

FIG. 32 is a flowchart showing another example of the procedureaccording to the third embodiment;

FIG. 33 is a flowchart showing an example of a procedure according to afourth embodiment of the present invention;

FIGS. 34A and 34B are diagrams showing an example of change in thedisplay of an object region having related information;

FIG. 35 is a diagram showing another example of the display of theposition of an object region having related information;

FIG. 36 is a diagram showing another example of the display of theposition of an object region having related information;

FIG. 37 is a diagram showing an example of display of a description listof an object region having related information;

FIG. 38 is a diagram showing an example of display of an object regionhaving related information with an icon;

FIG. 39 is a diagram of an example of display of, an object regionhaving related information with a map;

FIGS. 40A and 40B are diagrams showing an example of control of an imagereproducing rate for facilitating instruction of an object region;

FIG. 41 is a diagram showing an example which enables image capture forfacilitating instruction of an object region;

FIG. 42 is a flowchart showing an example of a procedure according to afifth embodiment of the present invention; and

FIG. 43 is a flowchart showing another example of the procedureaccording to the fifth embodiment.

DETAILED DESCRIPTION OF THE INVENTION.

A preferred embodiment of an object-region-data generating apparatusaccording to the present invention will now be described with referenceto the accompanying drawings.

First Embodiment

FIG. 1 is a block diagram showing the structure of a first embodiment ofthe present invention. As shown in FIG. 1, an object-region-datagenerating apparatus incorporates a video data storage portion 100, aregion extracting portion 101, a region figure approximating portion 102for approximating a region with a figure, a figure-representative-pointextracting portion 103, a representative point trajectory curveapproximating portion 104 for approximating representative points with acurve, a related information storage portion 105 and a region datastorage portion 106. A case will now be described in which the processaccording to this embodiment (in particular, processes arranged to beperformed by the region extracting portion 101 or the region figureapproximating portion 102) is configured such that the operation whichis performed by a user is permitted. In the foregoing case, the GUI (notshown in FIG. 1) is employed with which video data is displayed in, forexample, frame units to permit input of an instruction from the user.

The video data storage portion 100 stores video data and comprises, forexample, a hard disk, an optical disk or a semiconductor memory.

The region extracting portion 101 extracts a portion of regions of videodata. The portion of the regions are regions of an object, such as aspecific person, a vehicle or a building (as an alternative to this, aportion of the object, for example, the head of a person, the bonnet ofa vehicle or the front door of a building) in the video. Usually a videohas the same object in the continuous frames thereof. The regioncorresponding to the same object frequently changes owing to themovement of the object or shaking of a camera during an image pick-upoperation.

The region extracting portion 101 extracts an object region in eachframe corresponding to the movement or deformation of the object ofinterest. Specifically, the extraction is performed by a method ofmanually specifying a region in each of all of the frames. Anothermethod may be employed with which the contour of an object iscontinuously extracted by using an active contour model called “Snakes”as disclosed in “Snakes: Active contour models” (International Journalof Computer Vision, vol. 1, No. 4, pp. 321-331, July, 1988 disclosed byM. Kass et al.). Also a method disclosed in “Method of tracinghigh-speed mobile object for producing hyper media contents by usingrobust estimation” (CVIM 113-1, 1998, technical report of InformationProcessing Society of Japan) may be employed. According to thedisclosure, deformation and movement of the overall body of an objectare estimated in accordance with a position to which a partial objectregion has been moved and which has been detected by performing blockmatching. Alternatively, a method of identifying a region having similarcolors by performing growing and division of a region as disclosed inImage Analysis Handbook (Chapter-2, Section II, Publish Conference ofTokyo University, 1991) may be employed.

The region figure approximating portion 102 approximates an objectregion in a video extracted by the region extracting portion 101 with apredetermined figure. The figure may be an arbitrary figure, such as arectangle, a circle, an ellipse or a polygon. Also a method ofapproximating a region may be a method of performing approximation to afigure circumscribing the region. Another method of performingapproximation to a figure inscribing the region may be employed or amethod may be employed which is arranged such that the centroid of theregion is employed as the centroid of the approximate figure. Anothermethod of making the area ratio of the region and the approximate figureto be the same may be employed. As an alternative to the approximationof the object region with a predetermined type figure, the type of thefigure may be specified by a user for each object to which approximationis performed. Another method may be employed with which the type of thefigure is automatically selected in accordance with the shape of theobject or the like for each of the object to which approximation isperformed.

The approximation of the region with the figure is performed for eachframe whenever a result of extraction performed by the region extractingportion 101 is input. Alternatively, approximation with a figure may beperformed by using a result of extraction of a plurality of precedingand following frames. When the result of extraction of the plural frameis employed, change in the size and position of the approximate figureis smoothed among the plural frames so that the movement and deformationof the approximate figure are smoothed or an error in the extraction ofthe region is made to be inconspicuous. Note that the size of theapproximate figure may vary among the frames.

The figure-representative-point extracting portion 103 extractsrepresentative points of the approximate figure which is an output ofthe region figure approximating portion 102. The point which is employedas the representative point varies according to the type of the employedapproximate figure. When the approximate figure is formed into, forexample, rectangle, the four or three vertices of the rectangle may bethe representative points. When the approximate, figure is formed into acircle, the representative points may be the center and one point on thecircumference or two end points of the diameter. When the approximatefigure is an ellipse, the representative points may be the vertex of acircumscribed rectangle of the ellipse or the two focal points and,onepoint on the ellipse (for example, one point on the minor axis). When anarbitrary closed polygon is the approximate figure, the vertices may bethe representative points of the figure.

The representative points are extracted in frame units wheneverinformation about the approximate figure for one frame is output fromthe region figure approximating portion 102. Each representative pointis expressed by the coordinate axis in the horizontal (X) direction andthe coordinate axis in the vertical (Y) direction.

The representative point trajectory curve approximating portion 104time-sequentially approximates the sequence of the representative pointsextracted by the figure-representative-point extracting portion 103 to acurve. The approximate curve is, for each of the X coordinate and Ycoordinate of each representative point, expressed as a function of theframe number f or time stamp t given to the video. The approximationwith the curve may be approximation with a straight line orapproximation with a spline curve.

The related information storage portion 105 stores information (as analternative to this, information about the address at which relatedinformation stored in another storage apparatus, for example, Internetor a server on a LAN) relating to the object which appears in video datastored in the video data storage portion 100. Related information may bea character, voice, a still image, a moving image or their combination.Alternatively, related information may be data describing the operationof a program or a computer. Similarly to the video data storage portion100, the related information storage portion 105 comprises a hard disk,an optical disk or a semiconductor memory.

The region data storage portion 106 is a storage medium in which objectregion data is stored which includes data for expressing a formula ofthe curve approximating the time-sequential trajectory of therepresentative points which is the output of the representative pointtrajectory curve approximating portion 104. When related informationabout the object corresponding to the region expressed by a function hasbeen stored in the related information storage portion 105, objectregion data may include related information and the address at whichrelated information has been recorded. When information of the addressof recorded related information has been stored in the relatedinformation storage portion 105, also address information may berecorded. Similarly to the video data storage portion 100 and therelated information storage portion 105, the region data storage portion106 comprises a hard disk, an optical disk or a semiconductor memory.

The video data storage portion 100, the related information storageportion 105 and the region data storage portion 106 may be constitutedby individual pieces of storage apparatus. Alternatively, the overallportion or a portion may be constituted by one storage apparatus.

The object-region-data generating apparatus may be realized by asoftware which is operated on a computer.

The operation of the object-region-data generating apparatus willspecifically be described.

FIGS. 2A, 2B, 2C and 2D are diagrams more specifically showing asequential process. The sequential process includes a process which isperformed by the region extracting portion 101 to extract the objectregion. Moreover, a process which is performed by the region figureapproximating portion 102 to approximate the region and a process whichis performed by the figure-representative-point extracting portion 103to extract a representative point of a figure are included. Also aprocess which is performed by the representative point trajectory curveapproximating portion 104 to approximate the representative pointtrajectory with a curve is included.

In this case, the region figure approximating portion 102 employs amethod of approximating the region with an ellipse. Thefigure-representative-point extracting portion 103 employs a method ofextracting the two focal points of the ellipse and one point on theellipse. The representative point trajectory curve approximating portion104 employs a method of approximating the sequence of the representativepoints with a spline function.

Referring to FIG. 2A, reference numeral 200 represents a video of oneframe which is to be processed. Reference numeral 201 represents theobject region which is to be extracted. A process for extracting theobject region 201 is performed by the region extracting portion 101.Reference numeral 202 represents an ellipse which is a result ofapproximation of the object region 201 with an ellipse. A process forobtaining the ellipse 202 from the object region 201 is performed by theregion figure approximating portion 102.

FIG. 3 shows an example of the method of obtaining an approximateellipse when the object region is expressed by a parallelogram. PointsA, B, C and D shown in FIG. 3 are vertices of the parallelogram which isthe object region. In the foregoing case, calculations are performed sothat which side AB or side BC is a longer side is determined. Then, asmallest rectangle having portions of its sides which are the longerside and its opposite side is determined. In the case shown in FIG. 3, arectangle having four points A, B′, C and D′ is the smallest rectangle.The approximate ellipse is a circumscribing ellipse similar to theellipse inscribing the rectangle and passing the points A, B′, C and D′.

Referring to FIG. 2B, reference numerals 203 represent representativepoints of a figure expressing an ellipse. Specifically, therepresentative points are two focal points of the ellipse and one pointon the same (one point on the minor axis in the case shown in FIG. 2B).The focal points of the ellipse can easily be determined from points onthe two axes or a circumscribing rectangle of the ellipse. An examplewill now be described with which focal points F and C are determinedfrom two points P₀ and P₁ on the major axis and point H on the minoraxis shown FIG. 4.

Initially, a and b which are parameters of the major axis and the minoraxis, center C of the ellipse and eccentricity e are determined asfollows:E(P ₀ , P ₁)=2×aC=(P ₀ +P ₁)/2E(C, H)=be=(1/a)×{square root}{square root over ((a×a−b×b))}where E (P, Q) is the Euclidean distance between the point P and thepoint Q. In accordance with the determined parameters, the focal pointsF and G can be determined as follows:F=C+e×(P ₀ −C)G=C×e×(P ₀ −C)

Thus, the representative points F, G and H of the ellipse aredetermined. When the foregoing points are made to correspond to therepresentative points of the ellipse extracted in another frame,ambiguity is involved. That is, two combinations exist which make thetwo extracted focal points correspond to the two focal points in theprevious frame Since two intersections exist between the minor axis andthe ellipse, the intersection corresponding to the one point on theellipse extracted in the previous frame cannot be determined. A methodof determining the combination and the intersection will now bedescribed.

An assumption is made that the two focal points extracted in theprevious frame are Fp and Gp. To determine F or G which correspond toFp, the following comparison is made:E((Gp−Fp)/2, (G−F)/2) andE((Gp−Fp)/2, (F−G)/2)

When the former focal point is smaller, Fp is made to correspond to F,and Gp is made to correspond to G. When the latter focal point issmaller, Fp is made to correspond to G and, Gp is made to correspond toF.

An assumption is made that the intersections between the minor axis andthe ellipse in the previous frame are Hp and the intersections betweenthe minor axis of the ellipse in the present frame are H and H′. Thepoint H or H′ which must be made to correspond to Hp is determined bycalculating two distances:E(Hp−(Gp+Fp)/2, H−(F+G)/2) andE(Hp−(Gp+Fp)/2, H′−(F+G)/2)

When the former distance is shorter, H is selected. In a negative case,H′ is selected. Note that the intersection H between the minor axis andthe ellipse in the first frame may be either of the two intersections.

The foregoing process for extracting the representative points from theellipse is performed by the figure-representative-point extractingportion 103.

The representative points extracted by the foregoing process are usuallyvaried in the position among the successive frames owing to movement ofthe object of interest in the video or shaking of the image pick-upcamera. Therefore, the corresponding representative points of theellipses are time-sequentially arranged to perform approximation with aspline function for each of the X and Y axes. In this embodiment, eachof the three points F, G and H (see FIG. 4) which are the representativepoints of the ellipse requires a spline function for the X and Ycoordinates. Therefore, six spline functions are produced.

The approximation to a curve with spline functions is performed by therepresentative point trajectory curve approximating portion 104.

The process which is performed by the representative point trajectorycurve approximating portion 104 may be carried out whenever thecoordinates of the representative points of each frame relating to theobject region are obtained. For example, the approximation is performedwhenever the coordinates of the representative ports in each frame areobtained. Moreover, an approximation error is obtained to arbitrarilydivide the approximation region in such a manner that the approximationerror satisfies a predetermined range. Another method may be employedwith which the process is performed after the coordinates of therepresentative points in all of the frames relating to the object regionhave been obtained.

Reference numeral 204 shown in FIG. 2C represents the approximatedspline function expressed three-dimensionally. Reference numeral 205shown in FIG. 2D represents an example of the spline function which isthe output of the representative point trajectory curve approximatingportion 104 (only one axis of coordinate of one representative point isshown). In this example, the approximation region is divided into twosections (the number of knots is three) which are t=0 to 5 and t=5 to16.

The thus-obtained spline functions are recorded in the region datastorage portion 106 in a predetermined data format.

As described above, this embodiment enables the object region in a videoto be described as the parameter of a curve approximating atime-sequential trajectory (a trajectory of the coordinates of therepresentative points having the variable are the frame numbers or thetime stamps) of the representative points of the approximate figure ofthe region.

According to this embodiment, the object region in a video can beexpressed by only the parameters of the function. Therefore, objectregion data, the quantity of which is small and which can easily behandled, can be produced. Also extraction of representative points fromthe approximate figure and producing of parameters of the approximatecurve can easily be performed. Moreover, producing of an approximatefigure from the parameters of the approximate curve can easily beperformed.

A method may be employed with which a basic figure, for example, one ormore ellipses are employed as the approximate figures and each ellipseis represented by two focal points and another point. In the foregoingcase, whether or not arbitrary coordinates specified by a user exist inthe region (the approximate figure) of the object (whether or not theobject region has been specified) can be determined by a simpledeterminant. Thus, specification of a moving object in a video canfurthermore easily be performed by the user.

The data format of object region data which is stored in the region datastorage portion 106 will now be described. A case will now be describedin which the representative points are approximated with a splinefunction. As a matter of course, a case in which the representativepoints are approximated with another function is performed similarly.

FIG. 5 shows an example of the data format of object region data forrecording the spline function indicating the object region in a videoand information related to the object.

ID number 400 is an identification number which is given to each object.Note that the foregoing data item may be omitted.

A leading frame number 401 and a trailing frame number 402 are leadingand trailing frame numbers for defining existence of the object havingthe foregoing ID number. Specifically, the numbers 401 and 402 are theframe number at which the object appears in the video and the framenumber at which the object disappears. The frame numbers are notrequired to be the frame numbers at which the object actually appearsand disappears in the video. For example, an arbitrary frame numberafter the appearance of the object in the video may be the leading framenumber. An arbitrary frame number which follows the leading frame numberand which precedes the frame of disappearance of the object in the videomay be the trailing frame number. The leading/trailing time stamp may besubstituted for the lading/trailing frame number. The object existenceframe number or object existence time may be substituted for thetrailing frame number 402.

A pointer (hereinafter called a “related information pointer”) 403 forpointing related information is the address or the like of the dataregion in which data of information related to the object having theforegoing ID number. When the related information pointer 403 forpointing related information is used, retrieval and display ofinformation related to the object can easily be performed. The relatedinformation pointer 403 for pointing related information may be pointerfor pointing data of description of a program or the operation of acomputer. In the foregoing case, when the object has been specified by auser, the computer performs a predetermined operation.

Note that the related information pointer 403 for pointing relatedinformation may be omitted when the objects are not required to performindividual operations.

The operation for describing the related information pointer 403 forpointing related information in the object region data will now bedescribed. As an alternative to using the pointer 403, relatedinformation itself may be described in object region data. The relatedinformation pointer 403 for pointing related information and relatedinformation may be described in object region data. In the foregoingcase, a flag is required to indicate whether the related informationpointer for pointing related information or related information has beendescribed in object region data.

The approximate figure number 404 is the number of the figuresapproximating the object region. In the example shown in FIG. 2A inwhich the object region is approximated with one ellipse, the number ofthe figures is 1.

Approximate figure data 405 is data (for example, the parameter of aspline function) of a trajectory of the representative point of thefigure for expressing an approximate figure.

Note that approximate figure data 405 exists by the number correspondingto the approximate figure number 404 (a case where the approximatefigure number 404 is two or larger will be described later).

The number of the approximate figure number 404 for object region datamay always be one (therefore, also approximate figure data 405 is alwaysone) to omit the field for the approximate figure number 404.

FIG. 6 shows the structure of approximate figure data 405 (see FIG. 5).

A figure type ID 1300 is identification data for indicating the type ofa figure serving as the approximate figure, the figure type ID 1300being arranged to identify a circle, an ellipse, a rectangle and apolygon.

A representative point number 1301 indicates the number ofrepresentative points of the figure specified by the figure type ID1300. Note that the number of the representative points is expressedwith M.

A pair of representative point trajectory data items 1302 and 1303 aredata regions relating to the spline function for expressing thetrajectory of the representative points of the figure. Therepresentative points of one figure require data of one pair of splinefunctions for the X and Y coordinates. Therefore, data of the trajectoryof the representative points for specifying the spline function existsby representative point number (M)×2.

Note that the type of the employed approximate figure may previously belimited to one type, for example, an ellipse. In the foregoing case, thefield for the figure type ID 1300 shown in FIG. 6 may be omitted.

When the representative point number is defined according to the figuretype ID 1300, the representative point number may be omitted.

FIG. 7 shows an example of the structure of representative pointtrajectory data 1302 and 1303.

A knot frame number 1400 indicates the knots of the spline function.Thus, a fact that polynomial data 1403 is effective to the knots isindicated. The number of coefficient data 1402 of the polynomial variesaccording to the highest order of the spline function (assuming that thehighest order is K, the number of coefficient data is K+1). Therefore,reference to a polynomial order 1401 is made. Subsequent to thepolynomial order 1401, polynomial coefficients 1402 by the numbercorresponding to the polynomial order (K)+1 follows.

Since the spline function is expressed in an individual polynomial amongthe knots, the polynomials are required by the number corresponding tothe number of knots. Therefore, data 1403 including the knot framenumber and the coefficient of the polynomial is described repeatedly.When the knot frame number is the same as the trailing end frame, itmeans the trailing end polynomial coefficient data. Therefore,termination of representative point trajectory data can be understood.

A case will now be described in which a figure except for the ellipse isemployed as the approximate figure.

FIG. 8 is diagram showing the representative points in a case where aparallelogram is employed as the approximate figure. Points, A, B, C andD are vertices of the parallelogram. Since three points of the fourvertices are determined, the residual one is determined. Therefore,three vertices among the four vertices are required to serve as therepresentative points. In the foregoing example, three points, which areA, B and C, are employed as the representative points.

FIG. 9 is a diagram showing representative points in a case where apolygon is employed to serve as the approximate figure. In the case ofthe polygon, the order of the vertices is made to be the order along theouter surface. Since the example shown in FIG. 9 has 10 vertices, all ofthe vertices N₁ to N₁₀ are employed as the representative points. In theforegoing case, the number of the vertices may be reduced by employingonly vertices each having an internal angle smaller than 180° as therepresentative points.

As described above, the foregoing process may be performed by softwarewhich is operated on a computer. FIG. 10 is a flowchart showing theprocess which is performed by the video processing apparatus accordingto this embodiment. When the video processing apparatus according tothis embodiment is realized by software, a program according to theflowchart shown in FIG. 10 is produced.

In step S11, video data for one frame is extracted from the video datastorage portion 100.

In step S12, the region of a predetermined object in the video isextracted. Extraction may be performed by a method similar to thatemployed by the region extracting portion 101.

In step S13, an approximate figure is approximated to region data whichis a result of the process performed in step S12. The approximationmethod may be similar to that employed by the region figureapproximating portion 102.

In step S14, the representative points of the figure approximated instep S13 is extracted. Also a method similar to that employed by thefigure-representative-point extracting portion 103 may be employed.

In step S15, approximation of the position of a representative pointtrain of the approximate figure in the successive frame with a curve isperformed. Also a method similar to that employed by the representativepoint trajectory curve approximating portion 104 may be employed.

In step S16, a branching process is performed. Thus, determination ismade whether or not the processed image is in the final frame or whetheror not the object in the processed frequency which is to be extractedhas disappeared from the image (or considered that the object hasdisappeared). In an affirmative case, the process is branched to stepS17. In a negative case (both of the cases are negated), the process isbranched to step S11.

In step S17, the approximate curve calculated in step S15 is recorded ina recording medium as object region data in accordance with apredetermined format.

The example has been described with which one figure is assigned to oneobject to roughly express the object region. The accuracy ofapproximation may be improved by making approximation to the region ofone object with a plurality of figures. FIG. 11 shows an example inwhich a plurality of figures are approximated to one object. In theforegoing case, a region of a person in the image is expressed with 6ellipses 600 to 605.

When one object is expressed with the plural figures as shown in FIG.11, a process for dividing the object into a plurality of regions mustbe performed. The process may be performed by an arbitrary method. Forexample, a method with which the object is directly divided withmanpower may be employed. In the foregoing case, a pointing device, suchas a mouse, is used to, on the image, enclose the region with arectangle or an ellipse. Alternatively, the region is specified with atrajectory of the pointing device. When an automatic method is employedas a substitute for the manpower, a method may be employed with whichclustering of movement of the object is performed to realize thedivision. The foregoing method is a method with which the movement ofeach region in the object among the successive frames is determined by acorrelation method (refer to, for example, Image Analysis HandbookChapter-3, Section II, Publish Conference of Tokyo University, 1991) ora method with gradient constraints (refer to, for example, Determiningoptical flow, B. K. P. Horn and B. G. Schunck, Artificial Intelligence,Vol. 17, pp. 185-203, 1981) to collect similar movements to form aregion.

Each of the divided regions is subjected to the process which isperformed by the example of the structure shown in FIG. 1 or theprocedure shown in FIG. 10 so that data of the approximate figure isproduced. In the foregoing case, the spline function, which must bedescribed in object region data of one object increases as the number ofthe approximate figures increases. Therefore, the structure of data isformed which includes approximate figure data 405 by the number (L inthe foregoing case) corresponding to the approximate figure number 404,as shown in FIG. 12.

As described above, the field for the approximate figure number 404 maybe omitted by making the approximate figure number to always be one(therefore, data of the approximate figure is made to always be one) tothe object region data. In the foregoing case, one object can beexpressed with a plurality of figures when object region data isproduced for each figure approximating one object (the same ID number isgiven). That is, approximate figure data (1) to approximate figure data(L) 405 shown in FIG. 12 is required to be substituted for partial data(1) to partial data (L) in a certain region (for example, a region 605).

When one object is expressed with a plurality of figures in thisembodiment, the same figure is employed. A mixture of a plurality typesof figures may be employed.

Variation of a method of use of region data produced and recorded inthis embodiment will now be described. Although a person, an animal, abuilding or a plant is considered as the object in a video, the processaccording to this embodiment may be applied to any object in the video.For example, a telop may be handled as an object in a video. Therefore,a process in which a telop is employed as the variations of the objectwill now be described.

The telop is character information added to the image. In U.S. characterinformation called a “closed caption” must be added. In broadcasts inJapan frequencies of use of telops have been increased. The telop whichmust be displayed includes a moving telop, such as a still telop, atelop which is scrolled upwards in the screen and a telop which isscrolled from right to the left of the screen. When the region in whichthe telop is being displayed is approximated with a figure to store thetelop character train as related information, the contents of the imagecan easily be recognized or a predetermined image can easily beretrieved.

The region extracting portion 101 performs a process by employing amethod with which a telop region is manually specified. Another methodmay be employed which has been disclosed in “Method of ExtractingCharacter Portion from Video to Recognize Telop” (Hori, 99-CVIM-114, pp.129-136, 1999, “Information Processing Society of Japan TechnicalReport”) and with which the brightness and edge information ofcharacters are employed to perform character train extracting method.Another method has been disclosed in “Improvement in Accuracy ofNewspaper Story Based on Telop Character Recognition of News Video”(Katayama et al. Vol. 1, pp. 105-110, proceedings of Meeting on Image(Recognition and Understanding (MIRU '98)) to separate background andthe telop from each other by examining the intensity of edges. Thus, thetelop region is extracted. Each character and each character train maybe cut from the obtained telop region. Edge information in the telopregion in successive frames is compared with each other to detect aframe in which the telop has appeared and a frame in which the same hasdisappeared.

The region figure approximating portion 102 performs a process toapproximate the telop region extracted by the region extracting portion101 with a rectangle. The number of the frequency in which the telop hasappeared is stored in the leading frame number of object region data(401 shown in FIG. 5 or FIG. 12). On the other hand, the frame in whichthe telop has disappeared is stored in the trailing frame number 402. Apointer for pointing the character train information of the telop isstored in the related information pointer 403 for pointing relatedinformation. As approximate figure data 405, rectangular region dataencircling the telop is stored. When each row of a telop composed of aplurality of rows is made to be an individual region or when eachcharacter is made to be an individual region, the number of rows orcharacters is stored in the approximate figure number 404. Rectangularregion data encircling each row or character, that is, approximatefigure data 405, is stored by the corresponding number.

The figure-representative-point extracting portion 103 and therepresentative point trajectory curve approximating portion 104 performprocesses as described above because any specialized portion for thetelop is included in the processes.

The character train information of the telop which has appeared isstored in the related information storage portion 105. Moreover, thepointer for pointing information above is stored in telop region data(object region data).

When a keyword has been input and a character train corresponding orrelating to the keyword is included in the character train informationof the telop, the frame and time at which the character train appearscan easily be detected. If the image is a news program, retrieval ofinteresting articles is permitted to look only the articles.

In the foregoing case, addition of a pointer for pointing object regiondata corresponding to the frame or time to the character traininformation of the telop facilitates the retrieval.

Thus, the telop is processed as described above. Variations of theobject may be applied to the method of using this embodiment.

Although the method of approximation using the ellipse has beendescribed in the structure shown in FIG. 2, an approximation methodusing a rectangle will now be described as another approximation method.

FIGS. 13A, 13B and 13C are diagrams formed into the same shape as thatof FIGS. 2A, 2B, 2C and 2D. In the foregoing case, the region figureapproximating portion 102 employs a method of approximating a regionwith a rectangle. The figure-representative-point extracting portion 103employs a method of extracting the four vertices of the rectangle. Therepresentative point trajectory curve approximating portion 104 employsan approximation method using a spline function.

Referring to FIG. 13A, reference numeral 2800 represents video data forone frame which is to be processed.

Reference numeral 2801 represents an object region which is to beextracted. A process for extracting the region 2801 of the object isperformed by the region extracting portion 101.

Reference numeral 2802 represents a result of approximation of theobject region with the rectangle. The process for obtaining therectangle 2802 from the object region 2801 is performed by the regionfigure approximating portion 102.

An example of the process for obtaining the rectangle 2802 shown in FIG.13A is shown in FIG. 14. That is, a mask image of the frame 2800 israster-scanned (step S60). When the subject pixel is included in theobject region (step S61), the minimum value is updated if each of the Xand Y coordinates is smaller than the stored minimum value. If thevalues are larger than the maximum value, the maximum value is updated(step S62). The foregoing process is repeated and checked for all of thepixels so that the minimum and maximum values of the pixel positionindicating the object region 2801 for each of the X and Y coordinatesare obtained. Thus, the coordinates of the four vertices of therectangle 2802 can be obtained.

Although the above-mentioned method is excellent in easiness of theprocess, a multiplicity of non-object regions are undesirably containedin the approximate rectangle 3002 when, for example, as shown in FIG.15, an elongated object 3001 exists diagonally with respect to a screen3000. When the elongated object is rotated, the size and shape of therectangle 2802 are changed. The foregoing facts sometimes obstructidentification and instruction of the object.

An example of the approximation method well now be described with whichthe size of the rectangle can be minimized (the number of the non-objectregions in the approximate rectangle can be minimized) and to which theattitude of the object can be reflected.

Referring to FIG. 16A, reference numeral 3100 represents a video for oneframe which is to be processed.

Reference numeral 3101 represents an object region which is to beextracted. A process for extracting the object region 3101 is performedby the region extracting portion 101.

Reference numeral 3102 represents a result of approximation of theobject region. As distinct from the rectangle 2802 shown in FIG. 13A,the foregoing approximate rectangle 3102 is inclined. Also only a smallnumber of the non-object regions exists in the region 3102. When thesubject has been rotated, the shape of the region 3102 is not changed.The process for obtaining the rectangle 3102 from the object region 3101is performed by the region figure approximating portion 102.

FIG. 17 shows an example of the process. The process is arranged suchthat a principal axis of inertia of the object region is obtained.Moreover, an approximate figure is obtained in accordance with theprincipal axis of inertia.

Referring to FIG. 16B, reference numeral 3103 represents the centroid ofthe object region 3101.

Reference numeral 3104 represents the principal axis of inertia of theobject region 3101. Reference numeral 3105 represents a straight lineperpendicular to the centroid 3104.

Initially, inertia moments m₂₀, m₀₂ and m₁₁ of the object region areobtained (steps S70 to S72).

Assuming that the mask image is f(x, y), f(x, y) is 1 in the region 3101and 0 on the outside of the region 3101. The inertia moment of thesubject 3101 can be expressed as follows:m _(ij) =ΣΣx ^(i) y ^(j) f(x, y)

The inertia moment of f(x, y) with respect to a straight line y=x tan θpassing through the origin is obtained as follows:m _(θ)=∫∫(x sin θ−y cos θ)² f(x, y)dx dy

An assumption is made that the angle with which m_(θ) is minimized whenθ has beer, changed is θ₀. When only one set of angles exists, thestraight line y=x tan θ₀ is called the principal axis of inertia.

Note that tan θ₀ can be obtained as a solution of the followingquadratic equation:tan²θ+{(m ₂₀ −m ₀₂)/m₁₁} tan θ−1=0

When tan θ₀ is obtained around the centroid 3103, the relatedinformation of the object can be obtained (step S73).

Then, a straight line in parallel with the principal axis of inertia andcircumscribing the object region and a straight line perpendicular tothe principal axis of inertia and circumscribing the object region areobtained (step S74).

Referring to FIG. 16B, straight lines 3106 and 3107 are in parallel withthe principal axis of inertia 3104. The straight lines 3106 and 3107circumscribes the object region.

Straight lines 3108 and 3109 are straight lines in parallel with thestraight line 3105, the straight lines 3108 and 3109 circumscribing theobject region.

The rectangle 3102 is formed by the straight lines 3106, 3107, 3108 and3109 (step S75).

When the object is formed into a circle, the principal axis of inertiacannot be obtained. In the foregoing case, a procedure, for example, asshown in FIG. 14, may be employed to obtain an approximate rectangle.

The object region can sometimes more satisfactorily be expressed by anellipse as compared with expression by the rectangle. FIG. 18 shows anexample of a method of an approximate ellipse from a rectangle when theobject region is expressed with the rectangle. FIG. 19 shows an exampleof a process employed in the foregoing case.

Referring to FIG. 18, an assumption is made that an object region 3300and a circumscribing rectangle 3301 have been obtained.

Initially, the inscribing ellipse and the circumscribing ellipse of theapproximate rectangle 3301 are obtained (step S80).

Referring to FIG. 18, an ellipse 3302 is an inscribing ellipse of therectangle 3301 and the ellipse 3303 is an circumscribing ellipse of therectangle 3301.

Then, the size of the inscribing ellipse 3302 is gradually broughtcloser to that of the circumscribing ellipse 3303 (step S81). Then, anellipse 3304 for completely including the object region 3300 is obtained(step S82) to employ the ellipse 3304 as the approximate ellipse. Theunit for enlarging the size of the inscribing ellipse 3302 in eachprocess of the repeated process may previously be determined. The unitmay be determined in accordance with the difference between the size ofthe inscribing ellipse 3302 and that of the circumscribing ellipse 3303.

A reverse method may be employed with which the size of thecircumscribing ellipse 3303 is brought closer to the size of theinscribing ellipse 3302. In the foregoing case, the circumscribingellipse 3303 includes the object region 3300 from the first. Therefore,the ellipse previous to the ellipse with which the portion which is notincluded in the object region 3300 has first occurred in the repeatedprocess is required to be the approximate ellipse 3304.

Then, the figure-representative-point extracting portion 103 obtains therepresentative points of the approximate rectangle or the approximateellipse. The representative points of a rectangle may be the four orthree vertices of the rectangle. The representative points of theellipse may be the vertices of the circumscribing rectangle or two focalpoints and one point on the ellipse.

Then, the representative point trajectory curve approximating portion104 approximates the trajectory of the representative points obtained inthe time sequential manner with a spline function or the like. At thistime, it is important to bring the time sequences into correspondencewith each other. When the approximate figure is in the form of arectangle and having the representative points which are the vertices,the vertices of the adjacent frames must be brought into correspondencewith each other.

FIG. 20 shows an example of a method of a correspondence process. FIG.21 shows an example of the procedure of the correspondence process.

Referring to FIG. 20, reference numeral 3500 represents the centroid ofthe approximate rectangle. A rectangle 3501 in the previous frame and arectangle 3502 in the present frame have been obtained. Either of therectangle 3501 or 3502 is moved in parallel to make the centroids tocoincide with each other (a state in which the centroids have been madecoincide with each other is shown in FIG. 20). Distances d1 to d4between the vertices of the two rectangles are calculated to obtain thesum of the distances in the, combinations of all of the vertices (stepsS90 and S91). A combination with which the sum of the distances made tobe shortest is detected to establish the correspondence (step S92).

When representative points are obtained from the approximate figure, thenumber of combinations which is obtained in step S91 can be reduced whenthe representative points are obtained by a predetermined rule. When thecoordinates of the vertices of a rectangle are stored clockwise, onlyfour combinations is required for the correspondence.

The foregoing method sometimes has difficulty in realizing thecorresponding state. When the approximate rectangle is formed into asquare-like shape between the adjacent frames and the approximaterectangle has been rotated by 45°, the corresponding state cannot easilybe realized (because the sums of the distances are made to be similarvalues between the two combinations). In the foregoing case, a methodmay be employed with which the exclusive OR is obtained between theregions of the object in the approximate rectangle to employ acombination with which the area is minimized. Another method may beemployed with which an absolute difference between textures of theobject region is obtained to detect a combination with which thedifference is minimized.

An example will now be described in which when a trajectory of theobject region is described by the method according to the presentinvention, the structure of data which is different from the approximatedata structure shown in FIGS. 6 and 7 is employed.

FIG. 22 shows another example of a description format for data of theapproximate figure and data of trajectories of representative points ofthe object region. Note that FIG. 22 shows only one representative pointfor a portion (portion from knot number (N) 3902 to a functionspecifying information arrangement 3913) of data of the trajectory ofthe representative point (in actual, a plurality of representativepoints are described to correspond to the number of the representativepoints).

Description will now be made on the assumption that the highest order ofthe polynomial is the second order.

In the foregoing example (shown in FIGS. 5, 6 and 7), all of thecoefficients of the polynomial spline function are described. Thedescription method in this example is arranged to use combination of thecoordinate of the knot of the spline function and a value relating tothe second-order coefficient of the spline function. The foregoingdescription method has an advantage that the knot can easily beextracted to cause the trajectory of a large object to easily bedetected.

The foregoing description method will now be described.

The figure type ID 3900 shown in FIG. 22 specifies the type of thefigure which has been used to make the approximation of the shape of anobject. For example, only the centroid, the rectangle, the ellipse ortheir combination can be specified. FIG. 23 shows an example of types ofthe figures and assignment of the figure type ID. A representative pointnumber 3901 indicates the number of the trajectories of therepresentative points which are determined in accordance with the typeof the figure.

The knot number (N) 3902 indicates the number of knots of a splinefunction expressing the trajectory of the representative point. Theframe corresponding to each knot is expressed as time so as to be storedin knot time (1) to knot time (N) 3903. Since a predetermined number ofknot time has been provided, the knot time is described as knot timearrangement 3904.

Also x and y coordinates of each knot are described as arrangements 3906and 3908 of X coordinate 3905 of the knot and the Y coordinate 3907 ofthe knot.

A linear function flag 3909 indicates whether or not only a linearfunction is employed as the spline function between knots. If second orhigher order polynomial is partially employed, the foregoing flag 3909is turned off. Since the foregoing flag 3909 is employed, description offunction specifying information 3910 to be described later which isemployed when only the linear function is employed as the approximatefunction can be omitted. Therefore, an advantage can be realized in thatthe quantity of data can be reduced. Note that the flag may be omitted.

A function ID 3911 and a function parameter 3912 contained in functionspecifying information 3910 indicate the order of the polynomial splinefunction and information for specifying the coefficient of thepolynomial spline function, respectively FIG. 24 shows their examples.Note that ta and tb are time of continuous knots, f(t) is a splinefunction in a region [ta, tb] and, fa and fb are coordinates of the knotat time ta and tb. Since information about the knot is sufficientinformation when a liner polynomial is employed, no function parameteris described. When a quadratic polynomial is employed, one value isdescribed in the function parameter as information for identifying thecoefficient. Although the quadratic coefficient is employed in theexample shown in FIG. 24, another value, for example, one point on thequadratic curve except for fa and fb may be employed.

The foregoing description method is able to regenerate the splinefunction in all regions in accordance with information about the knotsand the function parameter under the limitation conditions shown in FIG.24.

Function specifying information 3910 exists by the number correspondingto knot number N−1, the function specifying information 3910 beingdescribed as an arrangement 3913.

Although the description has been made that the highest order of thepolynomial is the quadratic order, the highest order of the polynomialmay, of course, be a cubic or higher order.

The variations of related information will now be described.

FIG. 25 shows an example of the structure of data 4200 about relatedinformation for use in a monitor video. Actual data is required tocontain at least one item.

An object type 4201 is data indicating the type, such as a “vehicle” ora “person”, of an object to which approximation is made.

Identification information 4202 is data for identifying an actualobject, such as “name of a person”, “the license number of a vehicle” or“the type of the vehicle”.

An operation content 4203 is data indicating the operation, such as“walking” or “running” of the object.

FIG. 26 shows an example of the structure of data 4300 about relatedinformation for mainly use in a commercial contents or hyper mediacontents. Actual data is required to contain at least one item.

Name 4301 is data indicating name of the object. In a case where theobject is a character of a movie or the like, name of the player or theactor is specified.

Copyright information 4302 is data indicating information relating tothe copyright of a copyright holder of the object.

A copy permission information 4303 is data indicating whether or notvideo information in a range contained in the figure approximating theobject is permitted to be cut and re-used.

A foot mark 4304 is data indicating the time at which the object hasfinally been edited.

URL 4305 of related information formed by expressing data to which areference must be made when related information of the object isdisplayed by using URL.

Access limit information 4306 is data about informationpermission/inhibition of audience and jump owing to a hyper link foreach object and data for setting permission condition.

Billing information 4307 is data indicating billing information for eachobject.

Annotation data 4308 is data for aiding related information of theobject and the operation.

Since a relatively small number of related information items shown inFIGS. 25 and 26 exists, it is preferable that related information isdescribed in object region data.

A method of providing video data and object region data will now bedescribed.

When object region data produced owing to the process according to thisembodiment is provided for a user, a creator must provide object regiondata for the user by a method of some kind. The object region data maybe provided by any one of the following methods.

(1) A method with which video data, its object region data and itsrelated information are recorded in one (or a plurality of) recordingmedium so as to simultaneously be provided.

(2) A method with which video data and object region data are recordedin one (or a plurality of) recording medium so as to simultaneously beprovided. However, related information is individually provided orprovision of the same is not performed (the latter case is a case inwhich related information can individually be acquired through a networkor the like if provision is not performed).

(3) A method with which video data is solely provided. Moreover, objectregion data and related information are recorded in one (or a pluralityof) recording medium so as to simultaneously be provided.

(4) A method with which video data, object region data and relatedinformation are individually provided.

The recording medium is mainly used to perform provision in theforegoing case. Another method may be employed with which a portion orthe overall portion of data is provided from a communication medium.

As described above, the structure according to this embodiment is ableto describe the object region in a video as a parameter of a curveapproximating the time-sequential trajectory (the trajectory of thecoordinates of the representative points having the frame numbers ortime stamps as the variables) of the coordinates of the representativepoints of the approximate figure of the object region.

Since this embodiment enables the object region in a video to beexpressed with only the parameters of the function, object region data,the quantity of which can be reduced and which can easily be handled,can be generated. Moreover, expression of the representative points andgeneration of the parameters of the approximate curve can easily beperformed.

According to this embodiment, whether or not arbitrary coordinatesspecified by a user indicate the object region can considerably easilybe determined. Moreover, it leads to a fact that specification of amoving object in a video can furthermore easily be performed.

Other embodiments of the object-region-data generating apparatusaccording to the present invention will be described. The same portionsas those of the first embodiment will be indicated in the same referencenumerals and their detailed description will be omitted.

Second Embodiment

The first embodiment has the structure that the representative points ofa figure approximating the object region in a video is extracted so asto be converted into object region data. On the other hand, a secondembodiment has a structure that characteristic points in the objectregion in the video are extracted so as to be converted into objectregion data.

Description will be made about the different structures from thoseaccording to the first embodiment.

FIG. 27 shows an example of the structure of an object-region-datagenerating apparatus according to this embodiment. As shown in FIG. 27,the object-region-data generating apparatus according to this embodimentincorporates a video data storage portion 230, a characteristic-pointextracting portion 233, a characteristic-point-curve approximatingportion 234 for approximating the arrangement of characteristic pointswith a curve, a related information storage portion 235 and a regiondata storage portion 236.

Referring to FIG. 27, a video data storage portion 230 has the samefunction as that of the video data storage portion 100 according to thefirst embodiment. The related information storage portion 235 has thesame function as that of the related information storage portion 105according to the first embodiment. The region data storage portion 236has the same function as that of the region data storage portion 106according to the first embodiment.

The characteristic-point extracting portion 233 extracts at least onecharacteristic point from the object region in the video. Thecharacteristic point may be any one a variety of points. For example,corners of an object (for example, a method disclosed in “Gray-levelcorner detection, L. Kitchen and A. Rosenfeld, Pattern RecognitionLetters, No. 1, pp. 95-102, 1982) or the centroid of the object may beemployed. When the centroid of the object is employed as thecharacteristic point, it is preferable that the portion around the pointassumed as the centroid is specified and then automatic extraction isperformed.

The characteristic-point-curve approximating portion 234 has a basicfunction similar to that of the representative point trajectory curveapproximating portion 104 according to the first embodiment. That is,the characteristic-point-curve approximating portion 234time-sequentially approximates, to a curve, the positions of thecharacteristic points extracted by the characteristic-point extractingportion 233. The approximate curve is, for each of the X and Ycoordinates, expressed as the function of the frame number f or the timestamp t given to the video so as to be approximated with a curve bylinear approximation or approximation using a spline curve. Data afterthe approximation has been performed is recorded by a method similar tothat according to the first embodiment.

Note that object region data according to this embodiment is basicallysimilar to object region data according to the first embodiment (seeFIG. 5). The field for the approximate figure number is not required.Note that “data of the approximate figure” is “data of characteristicpoints”.

Also data of the characteristic point in object region data is basicallysimilar to data of the approximate figure according to the firstembodiment (see FIG. 6). Note that the “number of representative points”is the “number of characteristic points”. The “data of the trajectory ofrepresentative points” is the “data of the trajectory of characteristicpoints”. Note that figure type ID is not required.

Data of the trajectory of the characteristic points included in the dataof the characteristic points is similar to data of the trajectory of therepresentative points according to the first embodiment (see FIG. 7).

FIG. 28 is a flowchart showing an example of a flow of the process ofthe object-region-data generating apparatus according to thisembodiment. The overall flow is similar to that according to the firstembodiment. In step S21, video data for one frame is extracted from thevideo data storage portion 230 similarly to step S11 shown in FIG. 10.Steps S12 to S14 shown in FIG. 10 are made to be step S22 for extractingthe characteristic points of the object of interest. The approximationof the position of the representative point train of the approximatefigure in the successive frames with a curve in step S15 shown in FIG.10 is made to be step S23 for making approximation of the position ofthe characteristic point train of the object region in the successiveframes with a curve. Moreover, steps S24 and S25 are similar to stepsS16 and S17 shown in FIG. 10.

As a matter of course, the process according to this embodiment can berealized by software.

As described above, the structure according to this embodiment is ableto describe the object region in a video as a parameter of a curveapproximating the time-sequential trajectory (the trajectory of thecoordinates of the characteristic points having the frame numbers ortime stamps as the variables) of the characteristic points of theregion.

Since this embodiment enables the object region in a video to beexpressed with only the parameters of the function, object region data,the quantity of which can be reduced and which can easily be handled,can be generated. Moreover, expression of the characteristic points andgeneration of the parameters of the approximate curve can easily beperformed.

According to this embodiment, whether or not arbitrary coordinatesspecified by a user indicate the object region can considerably easilybe determined. Moreover, it leads to a fact that specification of amoving object in a video can furthermore easily be performed.

Note that object region data based on the representative points of theapproximate figure of the object region according to the firstembodiment and object region data based on the characteristic points ofthe object region according to the second embodiment may be mixed witheach other.

In the foregoing case, the format of object region data according to thefirst embodiment is provided with a flag for identifying a fact thatobject region data is based on the representative points of theapproximate figure of the object region or the characteristic points ofthe object region. As an alternative to providing the flag for theformat of object region data according to the first embodiment, when thefigure type ID has a specific value, a fact that object region data isbased on the characteristic points of the object region is indicated. Inthe other cases, a fact is indicated that object region data is based onthe representative points of the approximate figure of the objectregion.

The structure of object region data and a creating side have beendescribed. The portion for using the above-mentioned object region datawill now be described.

Third Embodiment

In the third embodiment, when object region data including relatedinformation has been given to the object in the video, a user specifiesan object (mainly on a GUI screen) to display related information(display of characters, a still image or a moving image, or output ofsound) or causes a related program to be executed.

FIG. 29 shows an example of the structure of a video processingapparatus according to this embodiment. As shown in FIG. 29, the videoprocessing apparatus according to this embodiment incorporates a videodata display portion 301, a control unit 302, a related informationdisplay portion 303 and an instruction input portion 304.

The video data display portion 301 displays video data input from arecording medium or the like (not shown) on a liquid crystal displayunit or a CRT.

The instruction input portion 304 permits a user to use a pointingdevice, such as a mouse, or a keyboard to perform an operation, forexample, specification of an object in the video displayed on the liquidcrystal unit or the CRT. Moreover, the instruction input portion 304receives input (specification of an object) from the user.

The control unit 302, to be described later, determines whether or notthe user has specified the object in the video in accordance with, forexample, the coordinates specified by the user on the screen and objectregion data input from a recording medium (not shown). Moreover, thecontrol unit. 302 makes a reference to the pointer for pointing relatedinformation of object region data when a determination has been madethat the user has specified a certain object in the video. Thus, thecontrol unit 302 acquires related information of the object to displaythe related information.

The related information display portion 303 responds to the instructionissued from the control unit 302 to acquire and display relatedinformation (from a recording medium or a server or the like through anetwork).

When the pointer for pointing related information is a pointer forpointing data in which program or the operation of the computer isdescribed, the computer performs a predetermined operation.

As a matter of course, also this embodiment may be realized by software.

A process which is performed when the object region is expressed as anapproximate figure similarly to the first embodiment will now bedescribed.

FIG. 30 shows an example of the process according to this example. Theflowchart shown in FIG. 30 includes only a process which is performedwhen a certain region in a video which is beings displayed duringreproduction of the video is specified by using a pointing device, suchas a mouse cursor (basically corresponding to the process which isperformed by the control unit 302).

In step S31, the coordinates on the screen specified by using thepointing device or the like are calculated. Moreover, the frame numberof the video which is being reproduced at the moment of the instructionis acquired. Note that a time stamp may be employed as a substitute forthe frame number (hereinafter the frame number is employed).

In step S32, the object existing in the video having the frame number inwhich the object has been specified is selected from object region dataof the object added to the video. The foregoing selection can easily beperformed by making a reference to the leading frame number and thetrailing frame number of object region data.

In step S33, data of a spline function (see FIGS. 6 and 7) extractedfrom object region data of the region selected in step S32 is used tocalculate the coordinates of the representative points of theapproximate figure in the video display frame number when the object hasbeen specified. Thus, two focal points F and G and point H on theellipse are obtained in the example according to the first embodiment(see FIGS. 2 and 4).

In step S34, it is determined whether or not the coordinates specifiedby using the pointing device or the like exist in the object (that is,the approximate figure) in accordance with the discrimination procedurewhich is decided according to the obtained representative points and thefigure type ID of object region data.

When the ellipse is represented by the two focal points and one point onthe ellipse similarly to the first embodiment, the determination caneasily be made.

When, for example, the Euclidean distance between points P and point Qis expressed by E (P, Q) similarly to the first embodiment, thefollowing inequality is held in a case where the coordinate P specifiedby using the pointing device exists in the ellipse:E(F, P)+E(G, P)≦E(F, H)+E(G, H)

In a case where the coordinate P exists on the outside of the ellipse,the following inequality is held:E(F, P)+E(G, P)>E(F, H)+E(G, H)

The foregoing inequalities are used to determine whether or not thespecified point exists in the object. Then, it is determined whetherstep S35 is performed or omitted (skipped) in accordance with a resultof the determination.

When a parallelogram is employed as the approximate figure of the objectregion in the video; four inequalities are used as a substitution forone inequality in the case of the ellipse to determine whether or notthe arbitrary coordinates exist in the object.

When, for example, points A, B and C shown in FIG. 8 are representativepoints, point D is obtained as follows:D=C+A−B

Then, an assumption is made that a point on a straight line passingthrough the points A and B is Q and the straight line is expressed bythe following equation:f _(A,B)(Q)=0

When the point P exists in the figure, the following two inequalitiesare simultaneously held:f _(A,B)(P)×f _(C,D)(P)<0, andf _(B,C)(P)×f _(D,A)(P)<0wheref _(A,B)(P)=(y _(A) −y _(B))×(x−x _(A))−(x _(A) −x _(B))×(y−y _(A))f _(B,C)(P)=(y _(B) −y _(C))×(x−x _(B))−(x _(B) −x _(C))×(y−y _(B))f _(C,D)(P)=(y _(D) −y _(C))×(x−x _(C))−(x _(D) −x _(C))×(y−y _(C))f _(D,A)(P)=(y _(A) −y _(D))×(x−x _(D))−(x _(A) −x _(D))×(y−y _(D)),andP=(x, y), A=(x _(A) , y _(A)), B=(x _(B) , y _(B)), C=(x _(C) , y _(C)),D=(x _(D) , y _(D))

When approximation to one object with a plurality of approximate figuresis made (refer to the approximate figure number shown in FIGS. 5 and12), the foregoing process is performed for each approximate figure.

In step S35, a process which is performed only when the specified pointexists in the object region. In the foregoing case, a reference to therelated information pointer 403 for pointing related informationcontained in object region data (see FIG. 5) is made. In accordance withinformation about the pointer, related information is acquired so as tobe, for example, displayed (in the example of the structure shown inFIG. 29, the foregoing process is performed by the related informationdisplay portion 303). When a program has been specified as relatedinformation, an specified program is executed or another specifiedoperation is performed. When related information has been described inobject region data, related information is required to be displayed.

FIG. 31 shows an example of a case where description (a text) of anobject in a video has been given as the related information. When thecoordinates specified by using the pointing device 802 duringreproduction of a video 800 exist in the object region 801 (a figureapproximating the object 801), related information 803 is displayed onan individual window.

In step S36, a branching process is performed so that it is determinedwhether or not an object having object region data furthermore exists inthe frame in which the object has been specified. If the object exists,the process proceeds to step S32. If the object does not exist, theoperation is completed.

When a plurality of regions overlap, either or both of the regions mayarbitrarily be selected.

A process which is performed when the object region is expressed ascharacteristic points of the object similarly to the second embodimentwilt now be described.

The portions different from those according to the first embodiment willmainly be described.

FIG. 32 shows an example of the procedure according to this example.Note that the flowchart shown in FIG. 32 includes only a process(basically, corresponding to the process which is performed by thecontrol unit 302) which is performed when a certain region in a videowhich is being displayed during reproduction of the video has beenspecified by using a pointing device, such as a mouse cursor. Since theoverall flow is similar to that of the flowchart shown in FIG. 30,different portions will mainly be described (steps S41, S42, S45 and S46are similar to steps S31, S32, S35 and S36).

In step S43, the coordinates of the position of the characteristic pointof an object in a displayed frame number are calculated from objectregion data. When a plurality of characteristic points exist, thecoordinates of all of the characteristic points are calculated.

In step S44, the distance between the position of the characteristicpoint calculated in step S43 and the coordinates specified by clickingis calculated for all of the characteristic points. Then, it isdetermined whether or not one or more characteristic point positioneddistant for a distance shorter that a predetermined threshold value.Alternatively, a process for calculating the distance for a certaincharacteristic point and comparing the distance with a predeterminedthreshold value is repeated. When one characteristic point positioneddistant for a distance shorter than the threshold value is detected, theprocess is interrupted. If one or more characteristic points distant fora distance shorter than the threshold value exits, the process proceedsto step S45. If no characteristic point of the foregoing type does notexist, the process proceeds to step S46.

As a result of the foregoing process, display of related information canbe performed in accordance with the coordinates of the characteristicpoint of the object when a portion adjacent to the region of theinterest has been specified by an operation using a pointing device orthe like.

Fourth Embodiment

A fourth embodiment will now be described with which an object regionhaving related information which can be displayed is clearly displayed(communicated to a user) by using object region data. In the foregoingcase, the object having related information which can be displayed mustpreviously be supplied with object region data including a pointer forpointing the related information.

The block structure of this embodiment is similar to that according to,for example, the third embodiment (see FIG. 29).

As a matter of course, also this embodiment can be realized by software.

A case in which the object region has been expressed as an approximatefigure similar to the first embodiment will now be described.

FIG. 33 shows an example of a process according to this embodiment.

An example case in which the approximate figure is an ellipse will nowbe described. As a matter of course, a similar process is performed in acase of another approximate figure.

In step S51, the frame number of a video which is being displayed isacquired. Note that a time stamp may be employed as a substitute for theframe number (hereinafter the frame number is employed).

In step S52, an object having the frame number acquired in step S51 andexisting in the video is selected. The selection is performed bydetecting data having a displayed frame number between the leading framenumber of object region data given to the video and the trailing framenumber.

In step S53, data of a spline function (see FIGS. 6 and 7) is extractedfrom object region data of the object selected in step S52. Then, thecoordinates of representative points of an approximate figure (or aregion having related information) in the displayed frame arecalculated.

In step S54, a reference to the figure type ID of object region data ismade to obtain an approximate figure expressed by the representativepoints calculated in step S53. Then, display of the image in eachapproximate figure (for example, an ellipse region) is changed.

The change may be performed by a variety of methods. When theapproximate figure is, for example, an ellipse, the brightness of theimage in the ellipse region is intensified by a predetermined value.Assuming that the degree of intensification is ΔY, the brightness beforethe change of the display is Y and an upper limit of the brightnesswhich can be displayed is Ymax, each pixel in the ellipse is displayedwith brightness of MIN(Y+ΔY, Ymax). Pixels on the outside of the ellipseare displayed with brightness of Y. Note that MIN(a, b) is a functiontaking a smaller value of a and b.

FIGS. 34A and 34B show an example with which the object region isdisplayed by the method with which the brightness is intensified (inFIGS. 34A and 34B, hatching indicates no change in the brightness and nohatching indicates intensified brightness). FIG. 34A shows a screen 1000which is in a state in which the display change process in step S54 hasnot been performed. Reference numeral 1001 represents an object havingobject region data in the video. A screen 1002 shown in FIG. 34B isdisplayed after the change in the display in step S54 has beenperformed. Reference numeral 1003 represents an ellipse regionapproximating the object region 1001. Display of only the inside portionof the ellipse region 1003 is brightened. Thus, a fact that the objectis an object which permits display or the like of related informationcan be recognized.

When one object is approximated with a plurality of approximate figures(refer to approximate figure number shown in FIGS. 5 and 12), theforegoing process is performed for each approximate figure.

In step S55, it is determined whether or not another object, the displayof which must be changed, exists. A determination is made whether or nota non-processed object having a display frame number which is betweenthe leading frame number and the trailing frame number exists. If thenon-processed object exists, the process from step S52 is repeated. Ifno object of the foregoing type exists, the process is completed.

As described above, display of an object region having the relatedinformation among the regions of the object in the video which isspecified by using object region data is changed. Thus, whether or notthe related information exists can quickly be detected.

A method of indicating the object region which permits display or thelike of related information may be the above-mentioned method with whichthe brightness in the object region is changed. Any one of a variety ofmethods may be employed. A variety of the methods will now be described.The procedure of each process using object region data is basicallysimilar to the flowchart shown in FIG. 33. Therefore, step S54 ischanged to a corresponding process.

A display method shown in FIG. 35 is a method of displaying the positionof an object having related information on the outside of an image 1600.Reference numerals 1601 and 1602 represent objects having relatedinformation. Reference numerals 1603 and 1604 represent bars fordisplaying the position of the object in the direction of the axis ofordinate and in the direction of the axis of abscissa. Display 1605 anddisplay 1606 correspond to the object 1601 having related information.FIG. 35 shows a structure that bars serving as marks are displayed inthe regions in which the region 1601 are projected in the direction ofthe axis of ordinate and in the direction 6f the axis of abscissa.Similarly, reference numerals 1607 and 1608 represent bars fordisplaying the object region 1602.

A state of projection of the object region in the foregoing directionscan easily be obtained by using the coordinates of the representativepoints of the approximate figure in the frame obtained from data of theapproximate figure of object region data and the figure type ID asdescribed in the embodiments.

It is preferable that the region of a different object is indicated witha bar displayed in a different manner (for example, a different color).

The method according to this embodiment causes a user to specify theinside portion of the image in accordance with the bars 1603 and 1604displayed in the vertical and horizontal directions on the outside ofthe image 1600 by using a pointing device. Thus, related information canbe displayed.

It is preferable that the region of a different object is indicated witha bar displayed in a different manner (for example, a different color).

FIG. 36 shows another display method with which the position of anobject having related information is displayed on the outside of animage 1700. Objects 1701 and 1702 each having related information existin the image 1700. The position of the object having related informationis indicated by an object-position indicating bars 1703 and 1704. Asdistinct from the example shown in FIG. 35, each display bar indicatesonly the position of the centroid of the object as a substitute for theobject region. Circles 1705 and 1706 indicate the centroid of the object1701. Circles 1707 and 1708 indicate the centroid of the object 1702.

Also the centroid of the object region in the foregoing directions caneasily be obtained in accordance with the coordinates of therepresentative point of the approximate figure in the frame obtainedfrom data of the approximate figure of object region data and the figuretype ID.

The foregoing method enables display which can easily be recognizedbecause the size of display on the object position indicating bar can bereduced if the object has a large size or many objects exit.

FIG. 37 shows an example of a display method with which a relatedinformation list is displayed on the outside of an image 1800. The image1800 contains objects 1801 and 1802 each having related information.Reference numeral 1803 represents a list of objects each having relatedinformation. The list 1803 shows information of objects each havingrelated information in the image frame which is being displayed. In theexample shown in FIG. 37, names of objects are displayed which areobtained as a result of retrieving related information from objectregion data of the objects existing in the frame.

The foregoing method permits a user to cause related information to bedisplayed by specifying the name shown in the related information list1803 as well as the specifying the region 1801 or 1802 with the pointingdevice. Since also instruction of the number shown in the list 1803enables related information to be displayed, the foregoing structure canbe employed in a case of a remote control having no pointing device.

FIG. 38 shows a display method with which objects 1901 and 1902 existingin an image 1900 and each having related information are indicated withicons 1903 and 1904 to indicate existence of related information. Theicon 1903 corresponds to the object 1901, while the icon 1904corresponds to the object 1902.

Each icon can be displayed by obtaining an approximate figure asdescribed above, by cutting a rectangle region having a predeterminedsize including the obtained approximate figure from video data in theframe and by, for example, arbitrarily contracting the cut rectangleregion.

The foregoing method enables related information to be displayed bydirectly specifying the icon as well as specifying the object region inthe video.

FIG. 39 shows an example of a display method configured to display a mapindicating the object region having related information so as toindicate existence of related information. An image 2000 includesobjects 2001 and 2002 each having related information. Reference numeral2003 represents a map of the regions of the objects each having relatedinformation. The map 2003 indicates the positions of the regions of theobjects each having related information in the image 2000. Referencenumeral 2004 represents the object 2001, while reference numeral 2005represents the object 2002.

The map 2003 has a form obtained by reducing the image 2000 and arrangedto display only the images of the object regions (only the approximatefigures obtained as described above are displayed at the correspondingpositions in the contracted image).

The foregoing method enables related information to be displayed byspecifying the object region 2004 or 2005 displayed on the map 2003 aswell as direct specification of an object in the image 2000.

FIGS. 40A and 40B show an example of the display method with whichspecification of an object existing in the image and having relatedinformation is facilitated by using a pointing device by controllingreproduction rate of the image at the position of the mouse cursor.Reference numerals 2100 and 2102 represent the overall bodies of thedisplay screens and reference numerals 2101 and 2103 represent regionson the display screens on which images are being displayed. In thedisplay screen 2100 shown in FIG. 40A, a mouse cursor 2104 is positionedon the outside of the image 2101 so that the image is reproduced at anormal display rate (frame/second)(or reproducing speed). In the displayscreen 2102 shown in FIG. 40B, the mouse cursor 2105 exists in the imageregion 2103. Therefore, display rate of the image is lowered ordisplayed image is frozen.

Another structure may be employed as a substitute for theabove-mentioned structure in which image display rate is always loweredor the displayed image is frozen when the mouse cursor has entered theimage region. That is, whether or not an object having relatedinformation exists in the frame is determined (determination is made bycomparing the frame number and the leading frame number/trailing framenumber with each other). If the object having related information existsin the frame, the image display rate is lowered or the displayed imageis frozen.

For example, an object which is moving at high speed in the video cannotsometimes easily be specified by using the mouse cursor. The foregoingmethod is arranged to change the reproducing speed according to theposition of the mouse cursor. Thus, movement of the object can be slowedwhen the object is specified or the displayed image can be frozen. Henceit follows that instruction can easily be performed.

FIG. 41 shows an example of the display method with which an objectexisting in the image and having related information can easily bespecified by using the pointing device. Reference numeral 2500represents an image which is being reproduced. Reference numeral 2501represents a button for acquiring an image. When the button 2501 isdepressed with a mouse pointer 2502, an image which has been displayedat the specified time can be acquired so as to be displayed on anacquired-image display portion 2503. The image 2500 is continuouslyreproduced even after the foregoing instruction has been performed withthe button 2501. Since the acquired image is displayed on theacquired-image display portion 2503 for a while, instruction of anobject which is being displayed in the acquired-image display portion2503 enables related information of the specified object to bedisplayed.

The button 2501 for acquiring an image may be omitted. A structure maybe employed from which the button 2501 is omitted and with which animage can automatically be acquired when the mouse cursor 2502 entersthe video display portion 2500.

A structure may be employed with which whether or not an object havingrelated information exists in the frame is determined when the button2501 has been depressed or the mouse cursor has entered the image region(for example, a determination is made by comparing the frame number andthe leading frame number/trailing frame number with each other). Onlywhen the object having related information exists in the frame, theimage is acquired so as to be displayed.

The foregoing method enables related information to easily be specifiedfrom a still image which is being displayed on the acquired-imagedisplay portion 2503.

The foregoing variations may be employed. Another method may be employedwith which the region of an image which permits display or the like ofrelated information is clearly displayed. Also a method may be employedwith which instruction is facilitated. Thus, a variety of methods foraiding the operation of the user may be employed.

A case in which the object region is expressed as characteristic pointsof the object similarly to the second embodiment will now be described.

Portions different from those according to the first embodiment willmainly be described.

A flowchart is, in the foregoing case, a flowchart which is basicallysimilar to that shown in FIG. 33 except for characteristic points beingemployed as a substitute for the representative points. Specifically,the coordinates of characteristic points of the approximate figure arecalculated in step S53.

FIG. 34 shows the structure that the brightness in the approximate FIG.1003 corresponding to the object 1001 is intensified. If three or morecharacteristic points exist in the foregoing case, a polygon having thevertices which are the characteristic points may be formed. Moreover,the brightness of the inside portion of the polygon may be intensified.If two or more characteristic points exist, a figure of some kind may beformed which has the representative points which are the characteristicpoints. Moreover, the brightness in the figure may be intensified.Alternatively, a figure, such as a circle, the center of which is eachof the characteristic points and which has a somewhat large size isformed. Moreover, each of the formed figure, which must be displayed, ismade conspicuous by means of brightness, color or blinking.

The structure shown in FIG. 35 is arranged such that projection of theapproximate figures corresponding to the objects 1601 and 1602 in thevertical and horizontal directions is displayed as the bar set 1605 and1607 or the bar set 1606 and 1608. If three or more characteristicpoints exist in the foregoing case, a polygon having the vertices whichare the characteristic points may be formed. Moreover, projection of thepolygon in the directions of the two axes may be displayed as the bars.If two or more characteristic points exist, a rectangle having thevertices which are the characteristic points may be formed. Moreover,projection into the directions of the two axes may be displayed as thebars. If one characteristic point exists, the foregoing method shown inFIG. 36 may be employed with which the position of the centroid isdisplayed with circles in the bars.

FIG. 38 shows the structure with which the image of an object isextracted by cutting in accordance with the approximate figure or thelike so as to be displayed as an icon. Also in the foregoing case, theimage of an object can be extracted by cutting in accordance with thecharacteristic points so as to be displayed as an icon.

FIG. 39 shows a structure that the approximate FIGS. 1903 and 1904 aredisplayed in a map. Also in the foregoing case, a figure of some kindformed in accordance with characteristic points as described above maybe displayed as a map.

The methods shown in FIGS. 37, 40 and 41 may employed in the foregoingcase.

The foregoing variations may be employed. Another method may be employedwith which the region of an image which permits display or the like ofrelated information is clearly performed. Also a method may be employedwith which instruction is facilitated. Thus, a variety of methods foraiding the operation of the user may be employed.

Fifth Embodiment

A fifth embodiment will now be described with which an object in a videois retrieved.

The block structure according to this embodiment is similar to thataccording to the third embodiment (see FIG. 29). Note that a structureshown in FIG. 29 may be arranged such that the related informationdisplay portion is omitted (for example, a system may be employed withwhich retrieval of an object is performed without use of relatedinformation). Another structure from which the instruction input portionis omitted may be employed (for example, a structure may be employedwith which the GUI is not used to instruct the retrieval). As a matterof course, also this embodiment can be realized by software.

The third embodiment has the structure that the two focal points and onepoint on the ellipse are employed as the representative points when theellipse is employed. A structure will now be described in which threevertices of circumscribing rectangle of an ellipse are employed as therepresentative points of an ellipse. As a matter of course, theretrieval is permitted regardless of employment of the representativepoints.

Note that the following symbols V₁ to V₄, P, Q, F₁, F₂, C₀, T, U and Care vector quantities.

Since the present invention is configured to describe the trajectory ofthe object region, estimation of points through which the object haspassed and points through which the object has not passed enables theobject to be estimated. For example, retrieval such as “retrievevehicles which have passed through the center of this crossing andentered that traffic lane” or “retrieve vehicles which have entered theroad from this position and which have not moved to this traffic lane”can be performed.

FIGS. 42 and 43 show an example of the procedure for performing theforegoing retrieval.

FIG. 42 shows an example of the procedure which is employed when arectangle is employed to express an object.

An assumption is made that point Q has been specified as the pointthrough which the object has passed and has not passed.

In step S100, time at which an object has appeared at time t is set. Instep S101, the coordinates of representative points V₁, V₂ and V₃ atcertain time t are extracted. The coordinates are calculated as thevalues of spline functions at the corresponding time. The coordinates ofthe residual vertices can easily be obtained in accordance with thethree vertices of the rectangle, as follows:V ₄ =V ₁ −V ₂ +V ₃

In step S102, the values of four functions expressed by the followingequations are obtained.f ₁(P)=(V _(2y) −V _(1y))×(x−V _(1x))−(V _(2x) −V _(1x))×(y−V _(1y))f ₂(P)=(V _(2y) −V _(3y))×(x−V _(2x))−(V _(2x) −V _(3x))×(y−V _(2y))f ₃(P)=(V _(3y) −V _(4y))×(x−V _(3x))−(V _(3x) −V _(4x))×(y−V _(3y))f ₄(P)=(V _(1y) −V _(4y))×(x−V _(4x))−(V _(1x) −V _(4x))×(y−V _(4y))where V_(i)=(V_(ix), V_(iy))

In step S103, it is determined whether or not the four obtained p=(x, y)functions satisfy the following relationship:f ₁(Q)×f ₃(Q)≦0 and f ₂(Q)×f ₄(Q)≦0

If the foregoing relationship is held, the object passes the specifiedpoint Q at time t. Therefore, it is determined that the object passesthrough the point Q (step S104). If the relationship is not held, theobject does not passes through the point Q at time t Then, whether ornot the object has passed through the point Q at another time isdetected.

In step S105, it is determined whether or not detection of all ofmoments of time t has been performed by determining whether or not timet is the same as time at which the object has disappeared from thescreen. If the two moments of time are the same, the process iscompleted and it is determined that the object has not passed throughthe point Q (step S107). If time t is earlier than time at which theobject has disappeared, t is incremented by one in step S106. Then, theprocess from step S101 is repeated.

The foregoing process is performed for all of the objects which is to beretrieved so that objects which satisfy the retrieval condition can beretrieved.

FIG. 43 shows an example of the procedure which is employed when anellipse is employed to express an object.

In step S110, time at which the object has appeared at time t is set.

In step S111 the coordinates of representative points V₁, V₂ and V₃ ofthe ellipse at certain time t are extracted. The representative pointsare the three vertices of the circumscribing rectangle of the ellipsewhich are successively and clockwise arranged in an order as V₁, V₂ andV₃. The calculation is performed by a process similar to that employedto process the rectangle.

In step S112, a, b and points F₁ and F₂ expressed by the followingequations are obtained (F₁ and F₂ are obtained as follows according tothe relationship in the magnitude between a and b):a=|V ₂ −V ₁|/2b=|V ₂ −V ₃|/2F ₁ =C ₀ +e(V ₂ −V ₁)/2 (when a>b) C ₀ +e(V ₂ −V ₃)/2 (when a≦b)F ₂ =C ₀ −e(V ₂ −V ₁)/2 (when a>b) C ₀ −e(V ₂ −V ₃)/2 (when a≦b)where C₀ and e are as follows (e is determined in accordance with therelationship in the magnitude between a and b)C ₀=(V ₁ +V ₃)/2e={{square root}{square root over ((a ² −b ²))}}/a (when a>b) {{squareroot}{square root over ((b ² −a ²))}}/b (when a≦b)

In step S113, it is determined whether or not the following conditionsare satisfied (the conditions vary according to the relationship in themagnitude between a and b).

condition when a>b:|F ₁ −Q|+|F ₂ −Q|≦2a

condition when a≦b:|F ₁ −Q|+|F ₂ −Q|≦2b

When the conditions are satisfied, the point Q exists in the ellipse attime t. Therefore, it is determined that the object has passed throughthe point Q and the process is completed (step S114). If the conditionsare not satisfied, the point Q exists on the outside of the ellipse attime t. Therefore, a. similar process is performed for other moments oftime t.

In step S115, it is determined as the completion condition whether ornot time t is time at which the object has disappeared. If time t istime at which the object has disappeared, it is determined that theobject has not passed through the point Q. Thus, the process iscompleted (step S117). If time t is not time at which the object hasdisappeared, t is incremented in step S116 and the process from stepS111 is repeated.

The foregoing process is performed for all of the objects which is to beretrieved so that the objects which satisfy the retrieval conditions areretrieved.

The foregoing process is arranged such that a fact whether or not thespecified point is included in the approximate figure is employed as thecriterion for making determination. A variety of criteria may beemployed. For example, it may be determined that the object has passedthe point when the specified point exists adjacent to the approximatefigure. Alternatively, it may be determined when the specified pointsare successively included in the approximate figure over a predeterminednumber of frames.

Also in a case where another figure is employed to express the shape ofthe object, a process corresponding to the figure is performed. Thus,objects which satisfy the retrieval conditions can be retrieved.

When a plurality of points of passage or a plurality of point ofnon-passage have been specified, the foregoing process is performed forall of the specified points.

As a matter of course, one or more points of passage and one or morepoints of non-passage may be combined with each other.

The retrieval can be performed by using the combinational logic for aplurality of points of passage and points of non-passage. For example,retrieval can be performed, for example, “retrieve objects which havepassed through either of point a or b and which have not passed throughboth of points c and d”.

The retrieval of the point of passage can be widened to a structure thattime for which the object exists at the point of passage. The foregoingretrieval includes “retrieve persons which have done free browsing for10 minutes or longer” and “retrieve persons who were in front of thecash dispenser for three minutes or longer”. To perform the foregoingretrieval, time for which the object exists at the input position ismeasured. Then, only the objects which exist at the input position fortime longer than time specified by the user are shown.

Another example of the widened retrieval will now be described in whicha condition in terms of the size (the area of the object) is added.

When the shape of the object is expressed by a rectangle or an ellipse,the area of the object at certain time t can be calculated as follows:

in the case of the rectangle,S _(R) =|V ₂ −V ₁ |×V ₃ −V _(2|)in the case of the ellipse,S_(E)=abπ

When the obtained value is used, retrieval can be performed by using acondition that, for example, the area is not smaller than S_(S) norlarger than S_(L). For example, when “retrieve persons which walk on theroad. Note that dogs and cats are not retrieved” is required, previousinstruction of an area larger than that of the dogs and cats enables theretrieving accuracy to be improved.

Another example of the retrieval will now be described with whichobjects which have moved through similar trajectories are retrieved.

An assumption is made that the trajectories of a first object and asecond object are T and U, respectively. Another assumption is made thattime for which the first object exists and time for which the secondobject exists are N_(T) and N_(U), respectively. An assumption is madethat N_(T)≧N_(U) in the foregoing case. Another assumption is made thattime at which each of the objects has appeared is t=0. The foregoingconditions can always be satisfied by changing T and U and by shiftingthe origin of the time axis.

In the foregoing case, distance d(T, U) between T and U is defined asfollows:${D( {T,U} )} = {\min\limits_{0 \leqq i \leqq {N_{T} - N_{U}}}{\sum\limits_{i,{j = 0}}^{N_{U}}{E^{2}( {{T(j)},{U( {j + i} )}} )}}}$

The coordinates of T at time t is expressed as T (t) and E(P, Q) showsEuclidean distance.

By using the distance between the trajectories, the distance-between thetrajectory of the object specified by the user and the trajectory ofanother object is calculated for all of the other objects. Thus, theobject exhibiting the shortest distance is displayed or the objectsexhibiting the short distances are displayed by the number specified bythe user. Thus, the objects which draw similar trajectories can beretrieved.

Moreover, an object which draws a trajectory similar to a trajectorydrawn by a user by an input device such as a mouse can be retrieved. Inthe foregoing case, the trajectory drawn by the user does not containtime information. Therefore, the direction between the trajectories mustbe calculated by a method distinct from d(T, U). Therefore, the distanced′(T, U) between the trajectory T and the trajectory U drawn by the useris calculated as follows:${d^{\prime}( {T,U} )} = {\sum\limits_{i}^{N_{{PU} - 1}}{\min\limits_{0 \leqq j \leqq N_{T}}{E^{2}( {{T(j)},U_{i}} )}}}$

The trajectory drawn by the user is expressed by dot sequence U_(i)(0≦i<N_(PU)). Note that N_(PU) is the number of the dot sequences. Oneor more objects exhibiting the short distance are displayed at objectseach drawing the similar trajectory. Thus, retrieval can be performed.

When the trajectory of the center of the object has been described,objects exhibiting short distance d(T, U) is retrieved such that thetrajectories are T and U. When only information of a rectangleapproximating the shape of the object or the trajectory of an ellipsecan be obtained, the trajectory of the center is estimated. Then, thedistance between the trajectories of the objects is calculated. Anestimated value of center C at certain time t is obtained from thecoordinates V₁, V₂ and V₃ of the vertices of the rectangle or theellipse as follows:C≈(V ₁ +V ₃)/2

As a result of the estimation, similar trajectories can be retrievedfrom the trajectories of all of the objects.

Although the example has been described in which the representativepoints of the approximate figure of the object region are employed, thepresent invention may be applied to a case where the characteristicpoints of the object region are employed similarly to the secondembodiment. In the foregoing case, whether or not the object has passedthrough the specified point is determined in accordance with a factwhether or not the distance between the characteristic point and thespecified point is shorter than a reference value.

The foregoing embodiments and structures may arbitrarily be combinedwith one another.

Each of the foregoing structures may be realized by a recording mediumstoring a program for causing a computer to execute a predeterminedmeans (or causing the computer to act as a predetermined means orcausing the computer to realize a predetermined function).

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the present invention in its broaderaspects is not limited to the specific details, representative devices,and illustrated examples shown and described herein. Accordingly,various modifications may be made without departing from the spirit orscope of the general inventive concept as defined by the appended claimsand their equivalents.

The present invention is configured such that the object region in avideo is described as the parameter of a function approximating thetrajectory obtained by arranging positional data of representativepoints of the approximate figure of the object region or thecharacteristic points of the object region in a direction in whichframes proceed. Therefore, the region of a predetermined object can bedescribed with a small quantity of data. Moreover, creation and handlingof data can easily be performed.

According to the present invention, a user is able to easily instruct anobject in a video and determine the object.

According to the present invention, retrieval of an object in a videocan easily be performed.

1. A data signal for use in a video decoding apparatus and fordescribing information of a moving object region in a video sequence,comprising: time data including a start time and a duration time of theobject region in the video sequence; type data being an integer, theinteger specifying a type of figure, corresponding to the object region,to be an ellipse, the integer also specifying a number of representativepoints of the figure; and figure data specifying a trajectory of atleast one of the representative points, including: time arrangement dataincluding times of points used to determine the trajectory, key valuedata representing values of the points used to determine the trajectory,and function data for indicating the trajectory of at least one of therepresentative points using function identifier, the function identifierindicating an order of a function used to determine the trajectory orthat no function is defined.
 2. A data signal of claim 1, wherein: thefunction data is used to indicate the trajectory using a formula:ƒ(t)=ƒ_(a)+ν_(a)(t−t _(a)), where ν_(a)=(ƒ_(b)−ƒ_(a))/(t_(b)−t_(a)) whenan order of a function used to indicate the trajectory is first order,where t_(a) represents a time of a first point of the points used todetermine the trajectory, t_(b) represents a time of a second point ofthe points used to determine the trajectory, ƒ_(a) is a coordinate ofthe first point, ƒ_(b) is a coordinate of the second point, and t is atime of a point to be determined.
 3. A data signal of claim 1, whereinthe function data further comprises: parameter data specifying a secondorder coefficient for the trajectory when an order of a functionindicating the trajectory is second order.
 4. A data signal of claim 3,wherein the function data is used to indicate the trajectory using aformula:ƒ(t)=ƒ_(a)+ν_(a)(t−t _(a))+½a _(a)(t−t _(a))²,whereν_(a)=(ƒ_(b)−ƒ_(a))/(t_(b)−t_(a))−½a _(a)(t_(b)−t_(a)) when an order ofa function used to indicate the trajectory is second order, where t_(a)represents a time of a first point, t_(b) represents a time of a secondpoint, ƒ_(a) is a coordinate of the first point, ƒ_(b) is a coordinateof the second point, and t is a time of a point to be determined.
 5. Adata signal of claim 1, further comprising hypermedia information.
 6. Adata signal according to claim 1, wherein: the representative points ofthe figure are ordered clockwise.
 7. A data signal according to claim 6,wherein: the representative points of the figure are continuouslyordered.
 8. A data signal according to claim 7, wherein: the integerrepresents all of the representative points of the figure withoutomitting any representative points.
 9. A data signal according to claim1, wherein: the time arrangement data are sorted in increasing order.10. A data signal according to claim 1, wherein: the figure dataspecifies the trajectory of at least three successive frames.